This guide details the differences between the IMAP and POP3 protocols in an email client (Outlook, Microsoft 365, Thunderbird, Apple Mail, eM Client, etc.) and explains why it is crucial not to use them simultaneously for the same email address managed by Infomaniak.

IMAP (recommended)

IMAP is the synchronization protocol. Messages remain on the server and can be accessed from anywhere.

• Multi-device access: your emails are synchronized between your computer, your mobile device, and the Infomaniak Web Mail app.
• Collaborative work: ideal for shared mailboxes. If a user moves or deletes a message, the change is visible to everyone.
• Security: in the event of a computer failure, your messages remain saved on the server.

POP3 (specific use)

POP3 is a download protocol. Messages are retrieved to your computer and generally deleted from the server.

• Offline access: messages are stored locally on your hard drive.
• Major drawback: once downloaded, messages are no longer visible on the Infomaniak Mail web app or on your other devices.
• Risks: if you use the "keep a copy of messages on the server" option, you may experience duplicate downloads and synchronization errors.

Important: Never mix POP and IMAP

Using both of these protocols simultaneously for the same address causes major technical conflicts:

• Messages inexplicably disappear on certain devices.
• Repeated downloads of old messages that have already been read (especially on Outlook).
• Unnecessary saturation of storage space.

Tip:we recommend using IMAP with all your email software/clients.

Refer to these other guides to configure an account in IMAP or to switch from POP to IMAP.