Knowledge Base/Frequently Asked Questions by Section/Questions about Messages

Should I set up my email client with POP or IMAP?

Workspace Support Team
posted this on January 07, 2012 08:16

Your email can be accessed either over the Web or using an email client like Outlook. The Web interface gives you the most functionality and this would be our recommendation. But if  you want to use an email client, and,

  • you plan to use Microsoft Outlook, we recommend Outlook 2010 since Microsoft has ended support for all previous versions.
  • you plan to use a non-Outlook client, we recommend Mozilla Thunderbird since it is free and has regularly updated versions for both Windows and Macs. Click here to access the download page for Mozilla Thunderbird.

When you configure your email account in Outlook or other email client, you typically have the choice between POP (Post Office Protocol) and IMAP (Internet Message Access Protocol). We describe below some of the differences between these two protocols. In general, we recommend that you use IMAP because it keeps your various email clients and Smartphones in sync. Use of the IMAP protocol, however, requires that:

(a) you use an e-mail client that properly supports the IMAP protocol (e.g., Outlook 2007 or later);

(b) your network firewall does not block the ports required for IMAP connection (ports 143, 993, 587);

(c) your computer's anti-virus software does not block IMAP connections (e.g., AVG anti-virus software); and

(d) your network supports fast broadband connections with little or no interruptions.


We summarize below the recommended protocol (POP or IMAP) for different versions of Microsoft Outlook and other popular email clients. Differences between POP and IMAP are also described below.

 

POP versus IMAP: Recommendations for Popular Email Clients

Outlook 2003: POP

Support of IMAP is limited and Microsoft will not be fixing quite a few known bugs related to IMAP. In addition, .PST files associated with IMAP accounts in Outlook 2003 are limited to 2GB total size. The practical limit is much smaller if you a very large number of email that you need to access with IMAP.

 

Outlook 2007: POP or IMAP (if certain conditions are met)

The original version of Outlook 2007 contained several serious bugs related to IMAP; these were fixed by Microsoft in later Service Packs. For IMAP to work properly with Outlook 2007, you must have the latest version of Outlook 2007 (pushed by Microsoft in Service Pack 3) installed on your computer. To see if you have the latest version of Outlook 2007 installed on your computer, open Outlook 2007 and go to Help/About Microsoft Outlook. If you have the latest (and last supported) version of Outlook 2007, the first line in the About Microsoft Outlook popup will say:

Microsoft Office Outlook 2007 (12.0.6607.1000) SP3 MSO (12.0.6607.1000)

If it says something else, please download and install Service Pack 3 for Outlook 2007. Click here to download Service Pack 3 for Outlook 2007. If you do not have the latest version of Outlook 2007 installed, you should use POP.

You also need to be sure that both your network firewall and computer anti-virus software are not blocking the ports associated with IMAP connections (Port 143, Port 993, and Port 587). Ask your network administrator if you're not sure. Please note that IMAP regularly fails on computers that have AVG Anti-Virus software installed with and without email scanning.

 

Outlook 2010: IMAP

Microsoft significantly improved its support of IMAP in Outlook 2010. Among other improvements, you can now choose to move deleted emails to the Deleted Items folder on the server. This was not possible in earlier versions of Outlook. As with Outlook 2007, you need to be sure that both your network firewall and computer anti-virus software are not blocking the ports associated with IMAP connections (Port 143, Port 993, and Port 587). Ask your network administrator if you're not sure. Please note that IMAP regularly fails on computers that have AVG Anti-Virus software installed with and without email scanning.

 

Mozilla Thunderbird: IMAP

Mozilla Thunderbird supports IMAP on both Windows and Mac versions. This is a free email client. As with Outlook clients, you need to be sure that both your network firewall and computer anti-virus software are not blocking the ports associated with IMAP connections (Port 143, Port 993, and Port 587). Ask your network administrator if you're not sure. Please note that IMAP regularly fails on computers that have AVG Anti-Virus software installed with and without email scanning.

 

Mac Mail: POP or IMAP (if the number of emails is not “large”)

IMAP is supported by MacMail and works well as long as you do not have a large number of emails in your email folders. A good rule of thumb is no more than 5000 emails per folder. If you have more than this, we recommend that you use POP instead of IMAP.

 

POP and IMAP: What's the difference?

POP is a one-way pull technology without any two-syncing capability.

In a POP environment, you do a one-time download or pull of your emails and their attachments to your computer.  Afterwards, when you open an email, you are opening it from your computer. You have the option of leaving a copy of your emails on the server permanently or for a period of time if you want to access them from a different email client or directly on the server (typically over the Web). On your email client, however, there is no more connection between the emails you downloaded and the mail server. And on the server, if you choose to leave a copy, you must manage them separately directly on the server.

POP is a  perfectly fine protocol as long as you use a single email client. However, if you have multiple email clients, confusion typically sets in because the set of messages tied to your account are likely to be different on different clients. If you don't "Leave Copy of Messages on Server," once the first client pulls emails down, the second client no longer has these emails available to pull down. And the ones you pulled down in your second client are not available for your first client to pull down the next time around. And even if you "Leave Copy of Messages on Server", if you move or delete emails on one client, they will not be reflected on the server or the other clients. Basically, with POP, emails in your different email clients will be out of sync.


IMAP is a two-way sync technology that keeps your email folders and email messages in sync.

IMAP is a two-way email management protocol with two-way syncing; any change you make in any of your email clients with IMAP will synchronize with your account on the server and vice versa. This means an email read or deleted in your email client will also automatically be marked as read or deleted when you check your account later via webmail or on another email client (e.g., home computer). All actions on email folders and emails themselves (Move, Copy, Delete, Mark as Read, Flag) will be reflected across all email clients with the mail server. So no matter how you access your email, you will see the same email folders and emails, in the same state. Regardless of which client you performed the action.

When you use IMAP you are accessing all of your email folders and all emails (not just emails in your Inbox) on the email server in the Cloud.  IMAP does not simply pull down messages one-time from your mail server to your computer like POP3 does. You can think of an email client using IMAP as a window to your messages on the server. Although the messages appear on your computer while you work with them, they also remain on the email server. You can, however, choose to download the entire message with IMAP so that you can work with them offline.


                            POP_v_IMAP.png


The picture above illustrates the primary difference between POP and IMAP. In the example shown, the user has two email clients (i.e., Outlook configured on both an office computer and a home computer). With IMAP, the set of messages in both email clients will always be the same. This example also shows why, if you plan to use your Smartphone to access email, you should configure the email client on your Outlook as an IMAP account. This will ensure that all of your emails will be accessible on your Smartphone.

                                                            

 

 
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