IMAP operates completely differently compared to POP3, another protocol that is used to receive mail. The first difference is where the mails are stored. As stated, with IMAP the mail is stored on the server and is only downloaded once a user opens a message.

In contrast, POP3 retrieves the mail and saves it locally on the machine where the email client is installed and deletes the mail from the server thereafter. This, under some circumstances, may be beneficial because it reduces the possibility of the mailbox exceeding its capacity which will ultimately influence email deliverability when, for example, new emails won’t be delivered once the mailbox is full.

The drawback is that, with POP3 and because the emails are received locally on one machine, users aren’t able to retrieve their mails from anywhere.

Another difference is that users aren’t able to manage their mailbox when they retrieve mail from a POP3 server. So, any changes a user makes locally, like creating folders, or deleting mails have no effect on the POP3 mailbox.

Although each has benefits and drawbacks, the choice of using IMAP or POP3 comes down to the preferences and needs of the user. If the user needs to use an email account with many different devices and would like the ability to create their own folders, then IMAP will be best. If users use only one device, and need no form of management, POP3 will suffice.

Ultimately, when it comes to email deliverability, no matter of location or device, IMAP is far superior to POP3.