Differences Between IMAP and POP3

IMAP and POP3 are protocols for accessing emails stored on a mail server. You can configure your email software to access emails from your 1&1 IONOS email account using either IMAP or POP3. We recommend IMAP. In this article you will learn why.

IMAP (Internet Message Access Protocol)
  • Emails remain on the email server, allowing you to set up the account on multiple computers and devices to access your email, as well accessing them through WebMail.
  • Folders can be created on the server to better manage the messages. The folders then sync across all devices used to check your email.
  • Sent messages are also saved in the sent folder, allowing you to view sent emails from any computer or device.
  • The server saves the status of an email (e.g. read, unread, replied, etc.). This allows you to see the status from any computer or device.
  • Initially, only the header (sender, date, subject) of an email is loaded. You can then decide whether you want to download the complete email message.
  • Messages are deleted directly on the server without being downloaded first.
  • You won't lose your emails if your mobile device or PC is destroyed or stolen.
POP3 (Post Office Protocol version 3)
  • All your emails are downloaded to the computer or device checking the email. After the emails have been downloaded, they are removed from the mail server.
  • Once the emails have been downloaded to the computer or device, you can also access your emails even if the device has no internet connection.
  • Data such as emails and folders are not synchronized between different devices. This means that if you set up your email on your mobile device with POP3, the emails will be downloaded completely to your mobile device. POP3 removes the emails from the mail server. It will no longer be possible for you to read your emails in WebMail because they are already downloaded to your mobile device.

Please note: It is possible, but not recommended, to use set up the same email account using IMAP and POP3 on different devices. If you choose to do this, it's highly recommended to Leave a copy of all messages on the server for the device using POP3. This allows you to still access and manage emails using IMAP on other devices.


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