Email - How to Choose Between POP and IMAP


How to Choose Between POP and IMAP

Whenever users set up their email client program (Outlook, Mac Mail, etc.), they may be prompted to choose between POP3 and IMAP4 protocols for their "incoming server."  This article explains the pros and cons to both protocols along with our recommendations.


Post Office Protocol (POP) is the most commonly used email communication protocol.  According to Wikipedia: 

"POP supports simple download-and-delete requirements for access to remote mailboxes.  Although most POP clients have an option to leave mail on server after download, e-mail clients using POP generally connect, retrieve all messages, store them on the user's PC as new messages, delete them from the server, and then disconnect."
  • Best use of POP:  For a user's primary desktop or laptop computer.
  • Pros:  Allows you to store all messages directly on your computer.  You never have to worry about exceeding storage limits imposed by your email service provider.
  • Cons:  Most of your email messages will only be accessible on your computer.  Other devices (phones, tablets) will only see new messages not yet downloaded to your computer.  However, it is possible to keep a certain number of days' messages on the server to be accessible by all devices (see recommendations below).


Internet Message Access Protocol (IMAP) is a newer protocol for accessing email.  According to Wikipedia:

"E-mail clients using IMAP generally leave messages on the server until the user explicitly deletes them. This and other characteristics of IMAP operation allow multiple clients to manage the same mailbox."

  • Best use of IMAP:  For mobile devices (phones, tablets).
  • Pros:  Leaves all messages on the email server so they can be accessed and managed on multiple devices.  All email messages and folders are available on every device.
  • Cons:  Most email service providers (including SiteWizard) limit the amount of email storage available on the server.  Because messages are not automatically deleted from the server, it is very easy for users to run out of space. Users should avoid using IMAP on desktops / laptops unless they are very diligent about deleting old emails.

Our Recommendations

  • If you are using a desktop / laptop computer, you should configure your email client (Outlook, Mac Mail, etc.) to use POP3 to download messages.  This will ensure that all messages are downloaded to your computer and removed from the server.  Your computer will keep a full history of all email messages, and you won't need to worry about exceeding your storage limit on the email server.
  • Your mobile devices (phones, tablets) can use either POP3 or IMAP.  Mobile email clients do not automatically delete messages from the server, even if they connect using POP3.
  • If you are using POP3 on your computer, but you still need access to recent emails from a mobile device (phone, tablet), you can set your email client to leave some messages on the server.  Most mail clients like Outlook have a setting to "leave a copy of messages on the server" (see screenshot below).  You can set the number of days before messages are automatically removed.
With this setup, your mobile devices will be able to access recent messages, but your desktop / laptop computer will retain a complete history of all messages.

Outlook - Leave messages on server


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