Fix slow Outlook IMAP folder synchronization issues

You are reading this article because you have set up IMAP on your outlook and it seems to take a long time to sync the folders/emails.

The usual suspect, in this case, is there is a lot of emails on the mail server or slow internet or a combo of both.

Your Outlook email client has to download all the emails, folders and contents to your local computer, so depending on your internet connection speed, especially if it's slow, syncing can take a while as the sync process is resource-intensive.

IMAP is a very, very cool, underrated technology, but one of the drawbacks is that its resource-intensive when you fire it up the first time.

So remember, if you have a lot of emails or/and a slow internet connection, sync may take a while.

However, if you are sure the above is not the case, then try the methods below (number 2 usually works for us).

Try two things first.

1. Root your inbox*
2. Define Send and Receive Group settings.

If you are using Gmail, then rooting your inbox "might" result in lost mail on a permanent basis. We have NEVER had an issue with Outlook with a normal IMAP account, it seems on GMAIL you may lose data.
More information on this link: 

If those fail, try step, 3, to remove large folders from your sync.

The instructions below are for Outlook 2010. Earlier versions are similar.

Step 1 - Root Your Inbox

  1. Click on File.

  2. This will show you the account settings. Select your account, click on account settings and account settings again.

  3. This will show you your account list. Double click on the email account you want to change.

  4. Now you will see the IMAP settings. Go ahead and add INBOX to the settings as show below.

  5. Click done and close each box and then in the bottom toolbar you should see it "syncing".

Step 2 - Define send receive groups

  1. Click on Send/Receive > Send Receive Groups > Define Send/Receive Groups.

  2. Click on Edit button.

  3. NEXT STEP IS THE IMPORTANT BIT. Once done, click Ok button. 

    It might be a good idea to restart Outlook, this is optional but we find in many cases a quick restart after applying settings clears out some cobwebs.

    Step 3 - Define send receive groups

    1. Right-click on your email account and select IMAP folder.

    2. Before you query the IMAP server, uncheck the box shown below, otherwise, it will only show the subscribed folder. Once you have done that, click the query button.

    3. Now you can see which folders are subscribed and gives you the option to remove large folders from your subscription which will speed up the sync.

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