POP vs. IMAP

In addition to providing web hosting services we also provide email hosting services - both as part of our web hosting packages and as a standalone service.

Setting up and managing an email client can be a challenge, especially as more and more customers need to check their email on multiple devices (mobile, tablet, desktop etc.). One area of confusion I often see involving email configuration has to do with what email retrieval connection protocol to use - POP or IMAP.

There is no single answer as to whether you should configure your mail client to connect using POP or IMAP. Everyone works differently and there is no single solution that will work for everyone. This post is not meant to be a comprehensive tutorial on internet email but is written as an introduction to the POP and IMAP protocols with the goal of helping you to better understand and configure your email across multiple mail clients.

I want to begin by mentioning that our mail server supports both POP (Post Office Protocol) and IMAP (Internet Message Access Protocol). Most modern email clients such as MS Outlook and the native Apple iOS mail app, for example, can be configured to connect and retrieve email via either POP or IMAP.

When you retrieve your email mail using more than one device it is important to understand, for example, the effect that deleting an email on one device will have on the other. If one of your mail clients deletes the message from the server it will not be there to be retrieved by the other mail client.

When you connect via POP your mail client goes out to the mail server and requests any new messages to be downloaded. You can choose to leave a copy of your messages on the server for a specific amount of days or until you delete them manually from the server, or you can choose not to leave a copy on the server at all. These configurations are set in the account settings advanced tab in the case of Outlook.

An IMAP client on the other hand synchronizes the email on your device (mobile or desktop) with the contents of the mail server. When connected via IMAP your device will mirror exactly what is on the server, and vice versa, including the folder structure. If my mobile device is connected via IMAP and I delete an email it will also be immediately deleted from the server. This is one of the advantages of IMAP - that all your devices connected via IMAP will identical.

If my mobile device is connected via IMAP and I delete an email on that device that email will no longer be on the server for retrieval by another device.

If my Outlook desktop is connected via POP and it is configured to remove messages immediately then that message will be available in Outlook, but I will no longer see it on my IMAP connected mobile device or webmail, because Outlook will have deleted it.

Caution is in order for those considering changing their desktop Outlook configuration from POP to IMAP. As mentioned earlier IMAP connected devices mirror the folder structure of the server. Although the folder structure can be changed, if you have been using Outlook for a while you might have mature folder structures with lots of rules that will need to be recreated when switching to IMAP. Be sure and backup before experimenting with this type of configuration change.

When trying to understand how your current email configuration is behaving it is important to understand how polling works. Polling is the period of time that your POP mail client has set to check for new emails. Remember, polling is not applicable to IMAP connections because IMAP mail clients and servers are synchronized in (near) real time.

In this scenario, if I delete an email from my IMAP connected mobile device that was received 60 minutes prior, that email will have already been download to my Outlook desktop which would have checked (polled) for new messages several times since the message arrived at the server. Of course this is providing that Outlook is open and running on my desktop computer.

Hopefully this brief introduction has given you a better understanding of some of the differences between POP and IMAP. There are many advantages and disadvantages to each the details of which are beyond the scope of this post. As you can imagine there is a lot of information available on the internet regarding this issue.

Additional information regarding email configuration can also be found on our email support page