Understanding the difference between POP and IMAP

This guide explains the differences between IMAP and POP3 connection protocols from a software/mail client (Outlook, Microsoft 365, Thunderbird, Apple Mail, eM Client, etc.) and why they should never be used at the same time with (in particular) an email address managed by Infomaniak.

Benefits of IMAP / IMAP4

In IMAP, e-mails remain on the server and are therefore accessible from any device connected to the Internet via the web app Mail Infomaniak (online service) mail.infomaniak.com) or the mobile app Infomaniak Mail (application for iOS / Android smartphone or tablet).

Practical if your connection is permanent, if you want to access all your messages from multiple locations simultaneously (at home, on the move, on the way, etc.) and if several users share a service mailbox, from different workstations.

You will always have the same view of the messages on the server, each will see the same messages: if a message is erased by a user, the other users will no longer see this message. If it is moved to a folder on the server, all users will see this message in that folder.

Disadvantages

In principle, you need to be connected to the Internet to view messages (but some software/message customers, some mobile devices will allow you to display the inbox including without 4G/5G or Wifi connection).

Benefits of POP/POP3

E-mails are removed from the server and sent to the computer. They are therefore searchable even without internet connection. Practical if your connection is expensive or non-permanent or to keep a local version if you stop your subscription to the mail provider.

Disadvantages

Once returned to a device configured in POP/POP3, emails no longer appear on the web app Mail Infomaniak (online service) mail.infomaniak.com) or the mobile app Infomaniak Mail (application for iOS / Android smartphone or tablet). You can't be many to look at the same box as the messages are erased at each consultation, so you'll feel like you're missing or seeing some messages disappear. In addition, if you "keep a copy of the messages on the server" (software/message client option), the higher the number of duplicate emails kept, the greater the risk of encountering problems (see below).

Never mix POP and IMAP

It may happen that your email software/client, Microsoft Outlook in particular, starts to recover all messages including those you have already received and read in the past.

The cause is often a POP3 incoming server configuration with the option "Keep a copy of the messages on the server".

This configuration can work wonderfully for a while then problems can arise, such as re-downloading messages.

To avoid this, it is recommended to use the IMAP protocol: this other guide explains how to set up an IMAP account and this other guide allows to see the solutions to move from an existing POP account to IMAP.

If you still want to use POP3 protocol Avoid enabling the option to keep a copy of the messages on the server.