IMAP and POP3: Differences, advantages and disadvantages

In assessing the differences, advantages and disadvantages between IMAP and POP3, you must take into account the kind of user that will use the mailbox, what it will be used for and the internet access of the user.

In order for you to find the one that adapts the best to your needs, let´s comment on some points about each protocol.

IMAP (Internet Message Access Protocol)

The most significant features of the IMAP protocol are that the emails and inboxes are not on your computer but in the Cloud Server. This allows all your mails to be perfectly sinchronized when usually read emails from different computers or devices, or even from Webmail, since in any of them will show all your emails, which includes not only the emails of the input inbox but also the rest of the inboxes.

The main disadvantage of the IMAP protocol is that it is necessary to have an internet connection available all the time to review the messages and also, since they are stored on the server, it is necessary to review from time to time the space used by the emails in order to not surpass the capacity limit of the inbox.

Anyway, this disadvantage is “corrected” when using some email programs, such as Microsoft Outlook, since it is possible to activate the “Autofile” option in order to avoid the inbox filling up, this way it will automatically delete or store the older emails in local files.


  • Two-way communication between the email server and the email client, which allows several devices to work on the same account seeing the changes made by everyone.
  • Emails are on the server all the time, so accessing them can be done from any place by having a device with internet access.
  • In case of a failure in the computer where the inbox is setup, or if for any reason the account is deleted, it is always possible to recover the emails back.
  • Since emails are not directly downloaded in the device that accesses the mail server, it does not use local space.
  • It is possible to manage local files from the server.
  • It allows the search of messages through keywords.


  • It is not possible to access emails with no internet access. 
  • In case of an intensive use of the email service, a big amount of store room on the server is necessary.
  • The files that have been created with IMAP will not be read using POP (the only exception is the file of the input inbox).

POP3 (Post Office Protocol)

In case of the protocol POP3, the mail client program (Outlook, ThunderBird, Mail, etc) connects to the server and downloads all the emails on the device where you set up the account. This is the main advantage, since when downloading the mails, it is possible to read them even with no internet connection.

As additional information, POP3 is a protocol that was developed when the internet connections were with no flat rate, so the aim was to download the email and quickly disconnect and not have to connect every time that you want to check the email.

When downloading the messages each time you read the email, it is deleted from the server, freeing up space, so it is less likely the mailbox will get full and can’t receive new emails. However, nowadays there is the option to keep a copy of the messages in the server in order to be able to synchronize the incoming messages and review the email from different devices.


  • Being able to use a client mailbox to download them to a device or computer, and read them afterwards, even with no internet connection.
  • It is not necessary to have a big storage space on the mail server, since when downloading the mail, it is deleted.


  • If the device where the downlaoded email is stored, has a breakdown or is stolen, the emails are lost.
  • Sending a message from the client can take double of the time.
  • Depending on the message, it can consume resources of the system.

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