Outlook 365 taking too long to synchronize each time email is being checked

Rupert Dragwater

Rupert Dragwater

Senior Member
Outlook version
Outlook 2013 64 bit
Email Account
POP3
Operating system::    Windows 11
Outlook version:     Version 2603
Email type or host:    pop / imap / exchange
Every 5 minutes, Outlook is set to check my mail. I have 11 different email address, which are outlook.com / hotmail.ca / gmail.com. It seems each time, it's taking between 10 and 12 minutes to synchronizing to finish.
I also have many subfolders, but it seems this problem only began about a week ago. Any suggestions would help.
 
1 -- Show Progress

On the "Send/Receive" menu tab.
Click the "Send/Receive All Folders" ribbon button.
Click the "Show Progress" ribbon button.
Toggle the [Details] button if it's not showing each task.
This should show you how long it's taking for each email account.

2 -- Sync Errors

Ctrl+6 to switch to "Folders" in you Nav Pane.
For each account look in the "Sync Issues" folder and subfolders for any errors.
Open any Sync Issue messages to see the details.
 
Last edited:
You said, "Toggle the [Details] button if it's not showing each task.
This should show you how long it's taking for each email account."

If I understand you correctly, you mean when Outlook is checking for mail. When doing so, it will tell me how many minutes is left before synching. If you mean something else, let me know.

Secondly, Ctrl+6 only brings up a new webpage. Aside from that, I cannot see or find anything called "sync Issues" in any of my email accounts, including the one where 99.99$% of my subfolders are found.
Looking this up isn't giving me any help either. Further instruction is needed and please not, I am less than a novice when it comes to the technicalities with this stuff.
 
Rupert Dragwater said:
Every 5 minutes, Outlook is set to check my mail. I have 11 different email address, which are outlook.com / hotmail.ca / gmail.com. It seems each time, it's taking between 10 and 12 minutes to synchronizing to finish.
I also have many subfolders, but it seems this problem only began about a week ago. Any suggestions would help.
Click to expand...
Sounds like it might be choking on syncing too many accounts/folders at once, try increasing the send/receive interval and disable syncing for some less important folders or accounts. Also rebuilding the Outlook data file or clearing cache sometimes helps, kinda annoying but it works sometimes
 
I've done the following... Sync Only the Inbox: Use the "Use the custom behavior defined below" option in Send/Receive settings to only synchronize the Inbox.
Also, I have increased the time to every 15 minutes checking the mail. It seems to have helped but I'll post later if changes. I'll see if I can clear the cache in a bit. Thanks for your input.
 
Ok, I thought I should report back with the ongoing results or better, non-results as to my latest experiment. Checking mail still hangs, starting at 60 seconds then after going no where, suddenly it goes up to 2 minutes, then 4 minutes and so on.
Looking at one site, I'm reading concerning clearing and rebuilding the OST. If perchance I take this route, my question is, will that bring back all my email accounts in Outlook, or will I have to add them manually all over again?
Also, doing that, will it bring back all my subdirectories? Please advise.
 
Sync Issues Folder:
What do I need to know about synchronization issues folders in Outlook?

Show Progress:
The intent was to see which task are taking so long. As Outlook syncs each account it should show you what it's doing. e.g. Sending, Receiving, Syncing Folders. Is it only one account that takes so long? Or a specific step for an account?

1776502973731.png
 
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Rupert Dragwater said:
clearing and rebuilding the OST. will that bring back all my email accounts in Outlook, or will I have to add them manually all over again?
Also, doing that, will it bring back all my subdirectories?
Click to expand...
You have one OST file per email account. To see which file belongs to which account:

File -> Account Settings -> Account Settings.
On the | Email | tab, select an account and the OST file path will be shown at the bottom.

1776503654437.png


If you close Outlook and rename an OST file (xxx.ost -> xxx.ost_OLD) Outlook will recreate it the next time it starts. It will then resync all the folders for that account you have defined in your Send/Receive Groups.
Change send/receive group settings - Microsoft Support

But you will loose any data that was in any "This Computer Only" folders for that account. This is usually Contacts and Calendar. If there is any data in these folders for an account, you must Export it to a PST file before you rename the OST and then Import it back once the OST file has been rebuilt.

See: 1 -- Export any "This Computer Only" folders in the Answer by Hornblower409 Apr 16, 2026 in
outlook wont let me sign into my imap server - Microsoft Q&A

And: Import email, contacts, and calendar from an Outlook .pst file - Microsoft Support
 
I'm stumped already, for I do not see a "This Computer Only" under this particular email address.
Also, is this an alternative...
"To unsubscribe from IMAP folders in Outlook 365, right-click on your inbox or top-level folder, select IMAP Folders, click Query, select the desired folder, and click Unsubscribe. This removes the folder from your view without deleting it from the server."
The reason I'm asking this, is this is becoming a bit complex for a novice such as myself, but I'll await your further instruction.
Thank you for doing what you're doing to assist.
 
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