What protocol to use when configuring an email account can be a little confusing for some, especially for those new to using an <Email Client> which is what the Outlook program is that’s included in any version of Office (see: Understanding Email Accounts and Email Clients).
There are no shortages of articles that can be found on the web comparing POP3 and IMAP with the conclusion that using IMAP is vastly superior and “absolutely everyone” should be using IMAP instead of POP3. This is one person who disagrees with the blanket conclusion that one is better then the other for everyone on the planet. Kinda like watching a debate about which is better – Apple or Microsoft (Windows) with some advocating for one over another with some kind of religious fervor. While the focus of this article is on POP3 and IMAP, some background information on the Exchange protocol is also included for reference purposes.
Right answer: depends on what you’re requirements/need are – just like anything else in this world. Before going through different types of scenarios, first a quick overview of some essentials………..
Recap of protocol functionality
POP3
- one way download to your computer/device of the email account’s <Inbox> – no more – no less
- is an industry standard protocol applicable to any <email client> whether Outlook or something like ThunderBird etc
IMAP
- two way synchronization of email folders only. Your computer contains a mirror of what is contained on the server. Anything you do to email items (send new, delete etc) gets sync’d back up to the server.
- multiple devices can be configured using IMAP resulting in the same information be accessible across all devices in real-time (where real-time means “when the email client connects to and syncs with the IMAP email client”)
- contact/calendar data does not get sync’d so all data will always be local
- like POP3, this is an industry standard protocol applicable to all email clients
Outlook.com/Exchange
- Outlook.com uses Exchange and separated it out here simply for clarity’s sake given the hundred’s of millions of Outlook.com users. For the sake of simplicity, Outlook.com is a free email account from Microsoft. Most free email clients don’t support the Exchange protocol or do so with the use of an addin. Some commercial email clients like <emClient> do support Exchange.
- two way synchronization of all email folders including contacts & calendar in real time – same definition for “real-time” as included under IMAP
- the Exchange protocol is a proprietary to Microsoft
Where is the data stored
Each email client uses different different ways to store your email/contact data on your computer. For the purpose of this article, focus is going to be primarily on Outlook which stores data in either a PST or OST file (see: Understanding the difference between PST and OST files)
POP3
- all data is stored in a single PST file regardless of which Outlook version is in use
- standalone PST files can be created to store/organize information
IMAP
Where data is stored for an IMAP account depends on which version of Outlook is being used
- Outlook ‘2010 and earlier – email data is stored is stored in a PST file which is a “mirror” of what is one the server. If the PST file is not found when Outlook is opened a new one will automatically be created. Contact/Calendar info is stored in a separate PST file
- Outlook ‘2013 and later – all IMAP data is stored in a single OST file where the email data is a “mirror” of what’s on the server whereas the contact/calendar data is stored in folders with the added description of “This Computer Only”. If the information in the “This Computer Only” folders isn’t backed up, it will be lost if you delete the Imap account from Outlook (See: How to Protect Outlook ‘2013/’2016 Imap Contact/Calendar Data)
Exchange/Outlook.com
- All data is stored in an OST file which reflects all information stored on the server including contact/calendar data
Why do you care about how/where your data is stored? So that you know what data needs to be backed up on a regular basis to prevent a catastrophic situation.
How do accounts get configured in Outlook
- in the current versions of Outlook, a process known as <auto-discover> is used to automatically configure an email account. Using <auto-discover>, you enter your email address and password and Outlook will “try” and retrieve all the required information for the account and configure it accordingly. Which protocol ends up getting used by default in these cases depends on what the server supports but will be either Exchange for Outlook.com/Exchange email accounts and IMAP for all others unless the server doesn’t support IMAP (which is rare these days
- POP3 accounts should generally always be configured manually
Why this is important to know is because many people have/are migrating from a previous version of Outlook with email accounts configured using POP3, use <auto-discover> on the new installation and are completely surprised that things aren’t the way they used to. There is no requirement to use <Auto-Discover> to configure your email accounts.
POP vs IMAP considerations/caveats
- All IMAP email data is stored on the server which means that you will need to be cognizant of the email storage limits the ESP (email servive provider) ha imposed on your account. You may find that you won’t be able to store endless amounts of email going back years as you expect which means that historical data needs to be saved to locally stored PST files and deleted from the server
- Similarly, POP3 accounts allow you to “Keep Messages on the server” for either an indefinite or specified amount of time. Again, if messages are kept on the server, storage limits can become a factor.
- For POP accounts, once email has been downloaded from server’s <Inbox>, it can’t be downloaded again using the email client that originally downloaded it. Also, if you delete a message after it’s been downloaded and you have the “Leave Messages on server” option set for indefinite retention, you will have to log in to your email account directly via webmail (your browser) to delete anything from the server.
- For POP accounts, if you have 2 or more computers set to access the same email account and one of them doesn’t have the “leave messages on server” option correctly set, everything that that computer downloads will be deleted from the server and no other computer will see that data
So with all that………………
Which is better for you – POP3 or IMAP?
In many cases, the actual requirement for some may be that they only want to be able to share contact/calendar data with their phone or casual secondary tablet devices regardless of whether the account is POP3 or IMAP since neither protocol provides that functionality. For a simple solution to that see: How to share Outlook contact/calender data using POP3 and Imap accounts. The rest of this will focus only on POP3/IMAP email
Scenario 1 – One computer / no sync’ing with other devices
- in this case, POP3 would be the best choice without having to worry about any server storage limits etc
- remember you can always access your account from any device using webmail (your browser) with the caveat being that you can’t download any “sent” messages when accessing the account using Outlook & POP3. An ill-elegant solution is to send a BCC copy to yourself
Scenario 2 – Absolutely don’t want to have anything stored “in the cloud” (on the server) for whatever reason regardless of how many computer/devices are being used
- same answer as Scenario 1
- usually in this kind of scenario, one computer is considered the primary where most of the work is done and all important data is retained. The others would be considered “casual use” (or more specifically to deal with new email). A potentially viable solution in this case may be to set the primary computer to “Leave Messages on Server” for a predefined number of days (i.e. 14 days) and the secondary machines to “Leave Messages on server” indefinitely. The theory here being that you will always at least access all the machines within the specified time period. The reason for setting the secondary machines for indefinite retention is to ensure the primary machine always gets all email.
- as in Scenario #1 – the issue with POP3 is the <Sent items> for any messages you may respond to while using a secondary machine in which case the same solution applies
Scenario 3 – Multiple active computers/tablets etc
- The optimum solution would be to configure the email accounts using IMAP where each device will always access to the latest email data
- Where server capacity becomes a factor, one machine should become “primary” and email that is no longer required to be accessible “all the time”, then this data can then be saved to PST files for future reference
- If the purpose of email access on secondary machines is purely to deal with new incoming email as opposed to having to be able to access historical information, then a viable solution might be to configure the email account as both <POP3> and IMAP on the primary machine and only IMAP on the secondary machines. This would allow copy anything contained in the IMAP <sent items> folder to the corresponding folder in the POP3 folder tree.
- Important to remember that moving anything from an IMAP folder to a POP3 folder is going to result in those items being deleted from the server. If something is moved from the IMAP <Inbox> to another email folder you created in the IMAP account before the machine with the POP3 account has a chance to access the <Inbox> – those items will need to be moved manually for retention in local storage.
- The alternative solution that many people implement is maintaining one master copy of a PST file which gets copied from machine to machine as required with the latest version always getting copied back to the primary machine. When copying a PST file from location to another, be sure to always have Outlook closed on both the source and target systems to ensure that no data corruption occurs
Something frequently overlooked
Having access to all your critical information regardless of which computer you are using is accomplished simply and easily via the use of a remote-control desktop sharing program such as TeamViewer. If your primary computer always ends up being on then you can always connect to it regardless of where you are and retrieve whatever information you require, whether that’s something from a local Outlook PST file or anything else.