I recently upgraded from Windows 10 to Windows 11. Only reason was my wife’s laptop failed and her new laptop came loaded with Windows 11. I then upgraded my laptop to Windows 11 so I could provide support whenever there might be any problems or surprises.
After that change to my laptop I discovered I could not download files that came attached to emails received on my eM Client.
I reinstalled eM Client and did all kinds of cleaning up on my laptop but nothing fixed the problem.
Until today, when I discovered the reason.
I had re-installed eM Client and all other programs on my wife’s new laptop from her old laptop and everything worked perfectly. She had no problems opening any attached files to her incoming emails. everything was OK.
To cut a long story short, today I finally determined that the problem with my eM Client not being able to download attached files was caused by my installing the latest version of eM Client after I upgraded my personal older laptop to Windows 11. That new version was emclient-v9.1.2109.msi
When I installed eM Client on my wife’s new laptop I simply took and installed all software programs and data from her old laptop and that included emclient-v8.1.1087.msi . . . not the latest version.
This evening I decided to remove emclient -v9.1.2109.msi from my laptop to see if installing the older emclient-v8.1.1087.msi solved my problem.
It did.
My older em Client is now performing normally and my question is . . . . . Why doesn’t the latest version work?
I await your response with interest.
I discovered I could not download files that came attached to emails received on my eM Client
What happened when you tried to download attachments ?. Did you get an error message ?
Also could you even open attachments apart from downloading ?
Download icon just went round and round . . . . for ever.
Message said “couldn’t download”. Never got those attachments.
Download icon just went round and round . . . . for ever.
Sounds like either when eM Client was upgraded to V9.1.2109, it may not have updated 100% in the program somewhere so had problems downloading attachments, or when the mail database upgraded to a V9.1 database it possible got corrupted and again wouldn’t download attachments, or there is a program running in memory in the background that was interfering or blocking eM Client downloading attachments at the time. Lastly you may have an actual Windows 11 issue.
So suggest first backup eM Client via “Menu / Backup”. You can see when the backup is completed via “Menu / Operations”.
Then re-download eM Client V9.1.2109 from the release history page and try reinstalling again and try downloading attachments again. Close eM Client before installing the update.
If you still have the same downloading attachment problem spinning round and round and you have an IMAP, Exchange or iCloud account, go to “Menu / Accounts” and click on your account on the left and remove and re-add the account again via the automatic email wizard at the top or manual mail setup depending on your specific acct setup.
Next if you still cannot download attachments then its more than likely background program related. So if you have any eg: optional Antivirus programs or optional Firewall / Security programs or VPNs, “completely disable those” to test if any of those are interfering or blocking the attachments downloading which can sometimes happen “unless they are configured” to allow eM Client.
Lastly if still the same downloading attachment problem with Windows 11, check for any Windows updates and do any if available. You should also be running at least build 21H2 with all the patches up to date. Failing that you might have some sort of Windows registry problem and may need a new user profile setup or a complete reinstall of Windows 11 from scratch. Good luck 
.
I really appreciate all the time you took to respond.
Now that I can download attached files once again, I have no problems using the earlier version of eM Client. Don’t have the time or need to try all your suggestions but will check again in a few months’ time to see if anything has changed.
Again, many thanks.
Dick