Why should you use email clients

POP or IMAP - which email protocol should I use?

Thierry Nischelwitzer, web application programmer (until 2012)

What do I need this POP or IMAP for?

If you want to set up an e-mail account on the PC, the question quickly arises as to which method should be used to download the e-mails from the server. There are different variants, but the most common are certainly POP and IMAP. The clients (Outlook, Thunderbird, etc.) communicate with the servers (Bluewin, GMX, etc.) via these protocols.

What is POP?

POP stands for Post Office Protocol. It is the transmission protocol for emails. The client, for example Microsoft's Outlook, retrieves the e-mails using this protocol from a remote mail server, for example Bluewin. This technology is very limited in terms of functions. It is only used to check emails. The protocol dates from 1996 and is being replaced more and more by IMAP.

What is IMAP?

IMAP is no longer entirely new either, it dates back to 2003. With IMAP, unlike POP, e-mails are left on the server. This makes it possible to access the same e-mails from several devices.
Here is a small diagram that should show how IMAP works:

The emails are always on the server and you can access them from anywhere.

With IMAP, a folder structure can also be created on the server. This folder structure is synchronized with all clients accessing the IMAP account. In other words, if I create a “Colleagues” folder on my mobile phone, it will also be displayed on my computer.

Concrete example

Hans always calls up his e-mails from his computer at home. To do this, he uses Microsoft's Outlook, which always downloads the latest e-mails via POP. Now Hans has bought a new cell phone, which also downloads the e-mails automatically.

What happens now

When Hans checks the e-mails at home, they are saved on the computer and deleted on the server. This means that he can no longer access these e-mails with his new cell phone because they are no longer on the server.

This is where IMAP comes in

But so that Hans can now read the e-mails on the computer and on the cell phone, he should use IMAP. If he has reconfigured the devices, he can synchronize both devices with the server. If he now reads an e-mail on the PC, the e-mail is automatically marked as read on the mobile phone. This ensures that the same status is always available on all devices. The e-mails are no longer stored on the end device, but remain on the server.

What about security?

POP protocol

Since POP is a pure text protocol, the authentication data - i.e. user name and password - are transmitted in clear text, which represents a security risk.
There are extensions so that the password is not transmitted in clear text, but this is not supported everywhere. Even with POP, the connection can be made via SSL. Thus the connection between client and server is encrypted. Your e-mail operator must, however, support this.

IMAP protocol

IMAP works the same as POP, it is also a text protocol. Here, however, the server can forbid the client from transmitting the password as long as a secure connection has not yet been established. The encryption is the same as with the POP, namely via an SSL connection.

What should I use now?

If you can and use multiple devices, I would recommend IMAP. Unfortunately, this service isn't always free, but more and more is coming. However, if you only have one computer and always check your e-mails there, you can stick with POP.
But you shouldn't neglect security. If possible, the connection should be made via SSL. This means that nobody can intercept the password without permission or even read the e-mails.

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Thanks for these explanations. That helped. Hans Knaus, on February 26th, 2012 at 9:36 pm, POP can also set emails to stay on the server. so that wouldn't be a reason to switch from pop to imap. I'm not sure yet if I should switch from POP to IMAP. N. Hennig, on March 28th, 2012 at 8:05 am The difference is still that with POP all mails are downloaded. Even if you can leave it on the server. In principle, IMAP only subscribes to it. How it handles this, however, differs from mail to mail client. If the emails can only be downloaded on one computer, you can leave it on POP, otherwise I would recommend IMAP. In any case, I would encrypt the connection via SSL, if the provider allows it. Thierry Nischelwitzer, on March 28th, 2012 at 8:10 am What is it like when I want to access the mails via IMAP with a device WITHOUT active internet access via e.g. Thunderbird, i.e. just read without retrieving new ones. Roland, on December 21, 2012 at 8:20 pm Mozilla Thunderbird allows the messages of an IMAP mailbox to be synchronized for offline use. To do this, select "Download / synchronize now ..." under "File", "Offline". Felix Maag, on December 27, 2012 at 10:53 am, very informative. Thank you, thank you birgit, on March 26th, 2013 at 12:36 pm As a result, some Pop3 clients (also ancient ones support this) also offer the possibility of only fetching the headers and only fetching the whole mail when it is accessed, including leaving it on the server or delete, the difference between POP3 and LDAP is even smaller. Of course, SSL is recommended one way or another as soon as PW's go over the line. Chris, on April 16, 2013 at 12:07 pm Hello
Really good post. Just one small question: How do I delete the mail on the server? (If I leave all mail on the server, it'll take a few weeks until the box is full)
Thanks chris, on July 5th, 2013 at 7:50 am The mailbox size is usually decisive when messages are left on the server.
With IMAP, the messages are removed from the server after they are permanently deleted.
If you use POP, you can usually choose how many days the messages are to be left on the server or whether they should be deleted as soon as they are removed from the trash.
In Microsoft Outlook, the setting can be found when editing the account under “Additional settings” in the “Advanced” tab at the bottom under “Submission”. Felix Maag, on July 16, 2013 at 1:38 pm Thank you very much for the information! chris, on August 1st, 2013 at 10:39 am Your information is very good. I have a bluewin address and have been working with POP for years. Now I would like to switch to IMAP.

1) Can I work directly with the "Setup (Windows)" from swisscom-support?

2) How do I have to proceed so that old mails and the structure on my PC are retained? gust, on September 15, 2013 at 12:50 p.m. Hello everyone!
Is that right or wrong, someone who lives in Switzerland cannot have a gmx.ch with Imap, even if he pays for it?
Heard this several times but almost can't believe it!
Does anyone know about that?
Greetings and thanks for the answer!
Tom Tom, on December 26th, 2013 at 1:39 pm When I set up pop (PC outlook and laptop Thunderbird) then I would like to receive the mails (sunrise) on both devices.
I couldn't do that with POP, although the mail stays on the server. One of the two devices then appears to see the message as read and no longer fetches it.
Can you change that?
If I use IMAP, Thunderbird deletes the mail on the server for me, if I delete it in Thuderbird - I don't want that either. He should leave it on the server. With all the settings in the Thunder I couldn't do that either (although I made the settings under Storage space in the Thunder).
Can someone explain that to me?

Thank you in advance. Tobi, on March 6, 2014 at 7:09 p.m. Hello everyone,
I have set up my Microsoft Outlook again. Now I want to be able to read the e-mails on my mobile phone.
But as soon as I check my e-mails at home, I want my messages on my mobile phone to be deleted. Do I have to set up IMAP or Pop 3 now?
Greetings and thanks for the answer Odermatt, on April 15, 2014 at 2:10 pm @ Odermatt: You can set up the mailbox with POP. The smartphone does not normally delete the e-mails from the server after they have been picked up, but the PC at home will do this by default. The e-mails are deleted when you access them via Outlook and they disappear on your smartphone the next time you synchronize the mailbox. With Outlook you just have to make sure that you do not activate the option «Leave a copy of all messages on the server». Felix Maag, on April 23, 2014 at 2:28 pm I have recently been using outlook 365. How can I use this to make the inboxes of several mailboxes (freenet, unitymedia, gmx and web) visible in one central inbox. In Thunderbird this was called "grouped folder"? wolle02, on May 14th, 2014 at 11:22 pm Hello,

I work with an iMac and the mail program on it ([email protected] (upc.ch)). Now when I write emails I see them, but I don't see them on web mail. The other way around, of course. When I'm in Urlauf or elsewhere, I use web mail. But there I don't see the mails written with my mail program!
In Gmail this works with the folder: show all messages. Am I doing something wrong and if so, what should I do?
Thanks in advance rebeh.her rebeh.her, on June 2nd, 2014 at 10:45 am I'm at bluewin.ch and can't set up a pop account on my iMac in the mail.

But in the settings in "Mail" I can't find the choice anywhere whether you want pop or imaps.

Pop would be much easier for my applications because I would then not have duplicate emails on the iPhone and Mac. Got mail 7.3

Who knows how to do it? sascha, on September 14, 2014 at 1:15 pm The stupid thing about IMAP is that if I delete an email on one device (e.g. mobile phone) because I no longer want it there (space reasons ...) then it disappears all over.
@ sacha: very simple, when entering the new account data instead of clicking on next in the first window, press "old" beforehand, then instead of "create" a "next" appears, alternatively just enter the wrong password, then a window with a selection appears Pop or Imap :) ayas, on October 29th, 2014 at 9:22 pm Thank you, answered my questions .......! Mika Mueller, on March 20, 2015 at 9:45 am I manage my emails in Outlook 2010 on my laptop with POP3 and leave them all as a backup on the server. In Outlook I keep the current + 2 months in the inbox and in relevant folders, there also longer. Every month I delete the oldest month manually. Outlook is my local master administration program.

In addition, I would like to be able to read new emails from the current day that have not yet been read in Outlook on my Galaxy Note 4 in the Samsung mail program, only when away from home, and if necessary answer (with me as Bcc) or write new ones.

Back at home, these should also appear in Outook, but marked as already read so that I can manage them there.

On the Note 4, only the emails of the current day that have not yet been read should be visible. If I delete some there, then only on the device, not on the server as well.

Can I implement this concept?
- if yes how?
- Outlook with POP3 and Note4 with IMAP
- Outlook and Note 4 with IMAP?
- Set up mail server for POP3 and IMAP?

Can I change an existing account from POP3 to IMAP, or do I have to delete the POP3 first and then create the IMAP again?

Thanks for your support.
Ronald Ronald, on April 18th, 2015 at 11:07 pm Even after removing an email account, emails are being received on this account. How can I definitely delete the presumably "hidden" email account - so that the status is no longer checked when it is transmitted? Bernhard Aebischer, on May 26th, 2015 at 8:06 pm Even after removing an email account, emails are being received on this account. How can I definitely delete the presumably "hidden" email account - so that the status is no longer checked when it is transmitted? Bernhard Aebischer, on May 26th, 2015 at 8:07 pm how is it going when I use IMAP ... I am logged in to googlemail via another device, I see that my iMail program on my computer with the IP address from home was called up even though I was not there.

Can it be done automatically even though the computer is closed, a sync ... takes place? Or does that only happen when the laptop is opened and the mail client starts?

Thank you :) susi, on June 12th, 2015 at 6:33 pm Can I set up Outlook so that it picks up the mails on the server using IMAP (without deleting them) and then saves them in a directory on the PC ?
Unfortunately, through ignorance, I deleted a lot of emails without wanting to.
There is also the possibility to archive mails. Where is this file stored? On the PC or on the server again?

I would be so happy if someone could help me.

Thank you :-) @Inge, on June 30th, 2015 at 1:05 pm The freeware MailStore Home is suitable for archiving emails under Windows. This program can also be used portable on a USB stick and has a very fast Search.

Microsoft Outlook usually creates archive files locally. You can see where these are located in Outlook 2013 under «File» «Options» «Advanced» «Settings for AutoArchiving ...». There is a field «Move old elements to:» with the path. Felix Maag, June 30, 2015 at 1:48 pm The advantage of IMAP is also a disadvantage. When t-online signaled to me that my mailbox on the server would soon be full, I deleted everything there. The big frustration came when I found out on my computer that everything had been deleted there too. Telekom couldn't offer me a solution, so I went back to POP.
If someone has a tip on how to delete mails on the Telekom server with IMAP and still keep them on the computer without much trouble, I would be grateful. Of course you can make pdf files out of them and save them, but that's not the point. I want to continue to see it in the mail program (Mac). Thank you very much Jan Sahner, on July 15th, 2015 at 12:00 pm Outlook runs on iPad with various functions.
Now I have my Bluewin addr. attached to Outlook. I receive all incoming mails, but cannot answer them in Outlook or I use the G-Mail addr.
What am I doing wrong? Mario, on December 10, 2015 at 4:35 p.m. Attention! IMAP is definitely the protocol of the future. But those who work with Outlook (i.e. also use contacts, calendar and tasks properly) should keep their hands off it. As soon as an IMAP account is set up in Outlook (e.g. Outlook 2013), the functionalities of the contacts, calendar and tasks are limited. Then only "tinker" and emergency solutions help. If you also work with different systems (e.g. iPhone and Windows PC), new folders are always added to one or the other system, as the names for the folders are not standardized (e.g. trash, recycle bin , deleted item). After many attempts (also with the Microsoft hotline) I returned to the POP protocol. Matthias, on December 11th, 2015 at 10:22 am we retrieve our mails via Outlook 2003 from 1 computer with POP3 and a laptop with Outlook 2010 via IMAP. Is accessed @ web.de.
The old computer is to be decommissioned. Now we notice that the emails via the laptop only stay on the computer for 14 days and then disappear, they are not archived either, despite being auto-archived. The usual auto archiving is set on the old computer.
All server settings at WEB.de are set to delete = never.
Do I switch the laptop to POP3?
How do I change that? Do I have to delete the email address beforehand and set it up again on POP3?

E-mails should still be fetched from the office and at home. (2 laptops)
Thank you f. D. Help

MoBo, 05.02.16 MoBo, on February 5, 2016 at 11:48 a.m. How can I prevent the different e-mail programs (e.g. Outlook and Mac) from installing their program-specific folders on the server, which are then used with Mail -Request to be reinstalled on the computers in turn? For example, I have three different inbox folders, several wastebasket etc. on my computers - it's a mess. Dieter Behre, on July 17th, 2016 at 9:18 am There are options for changing the folder names in many e-mail programs.
In Apple Mail, when you mark the new folder, you will find the option under “Mailbox” “Use this mailbox as”.
On the iPhone, the setting can be found under «Mail, Contact, Calendar» under Accounts, select the account to be adjusted and under IMAP again. Adjust the folder in the account on “Advanced” and under “POST BOX BEHAVIOR”.
In Microsoft Outlook 2016 you can find the “root folder path” for the inbox in the account settings when you mark the account and click on “Change” under “Additional settings”, “Advanced”.
On the server side, there is the option of setting the "Special Use" flag for a folder so that the e-mail programs select the correct folder when connecting. However, the setting would have to be made by the operator of the e-mail server.Felix Maag, on July 18, 2016 at 10:34 am Hello, I am annoyed that the IMAP server keeps saying goodbye to the program .... ????

What should I do ... it really sucks!
Thank you for your valuable help ...
KURT KURT BAER, on November 28, 2016 at 4:26 pm Thank you very much for the clear words and the example.
In my opinion, another factor in favor of IMAP is that SPAM, Trojans, viruses, etc. can be deleted on the server before they are downloaded to a device, right? Thank you reader, on January 3, 2017 at 3:09 p.m. E-mails in the inbox were mistakenly deleted on the server. Now all e-mails in the inbox are deleted on all end devices. We have Outlook 2010 on one PC. Can I get the mails back from anywhere? How can emails be automatically saved on the PC with IMAP using the Outlook 2010 email program? We thank you very much for your support. Rebecca, on February 3, 2017 at 9:19 am I use a PC and a notebook, the Outlook.PST file is on a NAS with the setting to delete the mails on the server when they are accessed. This means that they are no longer visible on the smartphone after the update. POP3 accounts are set up on both computers.
What is the best setting here (IMAP or POP3) so that not all emails are on both computers, but can still be seen on the smartphone?
Thanks a lot for your answer. kge_oesi, on February 6, 2017 at 3:56 p.m. Hello,
I understand how I can delete mail from the server using IMAP, provided I delete it in my mail program. However, I still don't know how to get the mails deleted on the server if I don't want to delete them on my computer? I move them to different folders, but don't delete them - at some point my box on the server will be full?
Thank you for your answer. kk-fra, on September 11, 2017 at 1:12 p.m. You can simply delete emails on the server by logging into your provider's website. At least it has always worked that way at GMX and WEB ... Fabian, on November 20, 2017 at 2:04 p.m.
when I use IMAP everything is synchronized, that is, if I delete something in Outlook, it is also gone on the server, but if the server is full, because it is free and only has 1.5GB, at some point I cannot delete anything on the server I want to keep it, right?
with pop I delete what I don't need on the PC, I keep the rest in a folder, if the server is full, I delete it from the back for a few months and everything is fine! Jürgen, on December 4th, 2017 at 9:19 am Lots of questions - but no clear answers! Horst, on December 13th, 2017 at 6:58 pm I lost all my important emails due to this change (of course my fault) and don't know how to find them again.
Is there a tip? Börny, on February 26, 2018 at 4:59 p.m. Hello,

I know the post office is older, but maybe someone can help me. I have recently been checking my e-mails from two devices. On a PC via Thunderbird and on a netbook also via Thunderbird. In the transition phase, however, I had set POP3 for one account (on a netbook) and IMAP for the PC. The following happened: There were two emails in the inbox on the POP account. I found both emails in the IMAP account. There they were in the inbox for about 2 weeks ... until they suddenly disappeared. I do not find them on the server at GMX, nor in a folder called "Recycle Bin" or "Deleted" ... In the POP account, which by the way, I have now switched to IMAP, both mails are still available.

In GMX it is set that mails may NEVER be automatically deleted after a certain period of time. What only irritates me now is that the mails were apparently on the server for a while, because they were downloaded in Thunderbird via IMAP ...

I hope you can help me and understand my post. Thank you :-) Sophia, on April 11th, 2018 at 7:13 pm The chat is very old, but I'm a little dissatisfied with it. What is the difference between imap and pop3? With both formats I can leave the mails on the server and don't have to download them and ssl is standard anyway. I have a smartphone and a PC / notebook / tablet and work very well with pop3.

So why are there 2 formats? Holger Birker, on December 4, 2018 at 9:48 p.m. I reinstalled Outlook 2013 on my computer.
Now I wanted to re-import my old e-mails that I had previously exported to a pst file.
I got the following error message:

The items in the Inbox folder cannot be imported or exported. The “Inbox” folder cannot contain any subfolders. This is likely a limitation of the IMAP server. To create a folder that can contain subfolders, add “/” to the name when creating the folder.

What do you mean by that?

Siegmund Operhalski, on December 9, 2018 at 11:27 a.m. Siegmund Operhalski, on December 9, 2018 at 11:27 a.m. I set up an account with IMAP via Thunderbird. But if I delete a message in Thunderbird, it is also deleted in gmx. Why? Brigitte, on July 2nd, 2019 at 8:35 am @Brigitte
The message is deleted because the account is integrated via IMAP and everything is synchronized, i.e. also deletions. Remo, on August 8, 2019 at 4:22 p.m. We also now have 3 Office 2013 computers 2 x and a Mac. If I delete something on one computer with Office 2013, it's gone on the other too.

With the Mac I have a lot of subdirectories where I drag the mails into - unfortunately they are gone with Office 2013 ...

For me it's POP and IMAP ... so do everyone have to be on IMAP? anja, on August 9, 2019 at 01:29 a.m. POP, without being asked to leave it on the server,.

IMAP, the mail is deleted on one of the devices.

Pop or IMAP when the mail is moved from the main directory to a local directory.

If the mails for the other devices are no longer there, from the server (deleted).

I would suggest configuring the devices right away. Martin, on September 3, 2019 at 12:45 p.m. Hello,
Facts: Windows 10, MS Office 2016, Outlook 2016

For a few months now it has happened in outlook that emails that have already been read, moved to folders, edited and also deleted are reloaded when the program is started and displayed as new in the inbox. I have to sort out 250 emails again. Protocol POP 3. Does anyone know the phenomenon and know help? GuGa, on October 30, 2019 at 8:21 p.m. Hello,

my laptop is retiring after 8 years and has been replaced by a worthy successor.
I have Outlook on both of my PCs, as well as on the laptop. My smartphone and tablet also access my 5 mailboxes:
So far there have never been any problems.
Now I have set up the web.de mailbox as imap on the new laptop with Outlook2019.
On the old laptop with Outlook2016 it is set up as Pop3, with the setting to leave all messages on the server for 100 days.
The PCs with Outlook2019 address web.de via imap.
Now I have exported a current outlook.pst on the PC as a backup and imported this outlook.pst into the new Outlook2019 of the new laptop using the import function.
When I start Outlook on the new laptop, my web.de online mail memory is full within a few minutes and I cannot send or receive any further e-mails.
Since I unfortunately can't find the setting in the current Outlook2019 that the messages should stay on the server for 100 days, I also want imap and not pop3 for the web.de mailbox.
What am I doing wrong?
Why does the new Outlook2019 of the new laptop move thousands of old e-mails to web.de's online e-mail storage?
What am I doing wrong ?
All other mailboxes have also been created as imap in the new Outlook2019 of the new PC and do not cause this?
I have now deleted thousands of e-mails on web.de's online web servers three times at intervals of approx. 7-10 days. But every time I start the new Outlook2019 on the new laptop, the web.de online mail memory is full of old e-mails again within minutes. The imported outlook.pst comes from the PC which also uses Outlook2019 and which also manages web.de via imap.
It would be really great if someone could give me a helpful tip. Unfortunately, Web.de only has an expensive service hotline.
Thank you in advance for helpful answers.
Greetings and send the rest of Sunday desired ... Ingolf Lange, on January 19, 2020 at 2:44 pm Hello, my current problem: do not do 90% of all emails on the
iPhone. Now my daughter has to go to my laptop from time to time for school reasons, Outlook then marks any new emails as read and I don't recognize them as new on the iPhone. I have imap. How / where can I set that, even if my daughter uses the laptop, my emails are still as unread on mine
Mobile phone appear? Thanks ! Nesi, on January 21, 2020 at 4:00 pm Sorry, it should say "90% of my emails are done on the iPhone." Nesi, on January 21, 2020 at 4:02 pm Hello,

but that's not quite true what he wrote up there.
Because with POP3 I can call up emails from anywhere without deleting them on the server.

Is just a matter of setting the server provider.

Sinan Sinan, January 21, 2020 at 6:08 pm Great informative article!

For everyone interested in secure e-mail services: Mailfence also uses POP and IMAP. Mailfence is generally a little less known but is an interesting service. Have a free account for some private mail myself.

https://mailfence.com/ David94, on April 2nd, 2020 at 3:25 p.m. Hello,
I have now received the mails from several mail addressees (web.de, gmx.de) as undeliverable. The following error message can be found:
554: gmx.net (mxgmx114) Nemesis ESMTP Service not available No SMTP service Reject due to policy restrictions.

Can someone tell me what is going wrong there, what should be changed in the settings.
Device: PC, Windows 10, Outlook 2016, yahoo, POP

Thank you and greetings

GuGa Gattner, on June 8th, 2020 at 9:07 am hello,
When setting up imap, I now have the problem that they go to the inbox and when I go to them they go to the Trasch folder, where they are also deleted. Klaus-Dieter Reinhardt, on October 27, 2020 at 5:39 p.m.

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