Both POP vz IMAP are protocols used to receive email from a mail server. So, when somebody sends you an email, that emails arrives at your mail server, waiting for you to read it.

POP vz IMAP Mail

Pop is the older of the two protocols. The way POP mail works is that your email program (Outlook 2010, Outlook express, Thunderbird, or the email program on your smart phone) downloads the mail from the server, and then clears the messages from the server. This means that the only copy of those emails will be on your PC (or laptop or smart phone, etc).

With modern email programs it is possible to set the program to leave emails on the server for a certain period, eg, 14 days. If you have multiple devices all using POP, then setting this option in all of your device’s email programs allows you time to download the messages to all devices. 14 days later the emails are removed from the server and you have a copy on each of your devices.

IMAP vz POP Mail

IMAP works differently. IMAP does not download and store mail on your own PC. IMAP can be viewed (over simplification) as a mail reader. It reads mails from the server but it keeps them there. Each of your IMAP devices can read, edit, delete mail. A change on one device has an effect on all devices. For instance, if I use IMAP on my smart phone’s email program as well as in Thunderbird on my laptop, if I delete the mail on my phone, it will be removed from the server as well as the laptop.

IMAP is essentially a syncing protocol, what you do on one device is syncronised across all devices.

Which Protocol to Use?

This is not really an easy answer and you may be in a situation which favours one over the other. Most people tend to lean towards IMAP, HOWEVER, my personal feelings are that I prefer POP!

There are several reasons I personally prefer POP to IMAP:

Just because I don’t want a particular email on my phone (for instance) does not mean I don’t want it on my laptop. If I receive work and private mails to both devices, I might be compelled to keep the work mails on my laptop, but I may not want them to clutter my phone. With IMAP, if I delete from the phone I delete from all devices because its a synced operation

Similarly, if I accidentally delete a mail on one device, I’d like to know its still available on the others.

On shared hosting environments, IMAP can quickly cause you to run over the allowed disk space quota. Even when you delete a mail from your email account, it usually goes to a deleted folder. Same thing with junk mail and sent mail. All of those mails stay on the server and that can cause disk space problems for you.

My personal preference is to use POP and set them all to keep the mails on the server for a while. That way, all my devices can download the mail and yet my online storage space is not killed by having months or years worth of trash and spam emails and sent email folders left on the server.

OH, one more thing. A quick google search for “Your server reported a UID that does not comply with the IMAP standard” reveals that MS Outlook can sometimes get a little confused. This might happen when you’ve reached your disk space quota as described above and the IMAP server cannot write mails to disk, but it can also sometimes happen when more than one IMAP devices is working with the same mail at the same time.

Which do you use?

Do you have a preference? Please let me know by adding a comment below….