OS: 10.15.7
Machine: 2018 Mac Mini, 3.2 i7, 16GB RAM, 500GB SSD internal storage w/ ~200GB free (don't think it's underpowered hardware)
Connection: Hardwired Ethernet, 240-250Mbps Down/12-14 UP

The explanation is pretty simple. When I try to open mail, even when nothing else is open on my machine, it takes 1-2 minutes for the red badge to display on the Mail icon, and the main message window to open up/display.

I have 2 accounts set up with Mac mail, both IMAP. Neither gets a tremendous amount of email, less than 10 messages a day between the two of them.

I have no idea what's causing the slowdown. Any ideas on why this might be happening and what to do to address it? Thanks!

Silverstring said:

OS: 10.15.7
Machine: 2018 Mac Mini, 3.2 i7, 16GB RAM, 500GB SSD internal storage w/ ~200GB free (don't think it's underpowered hardware)
Connection: Hardwired Ethernet, 240-250Mbps Down/12-14 UP

The explanation is pretty simple. When I try to open mail, even when nothing else is open on my machine, it takes 1-2 minutes for the red badge to display on the Mail icon, and the main message window to open up/display.

I have 2 accounts set up with Mac mail, both IMAP. Neither gets a tremendous amount of email, less than 10 messages a day between the two of them.

I have no idea what's causing the slowdown. Any ideas on why this might be happening and what to do to address it? Thanks!

Click to expand...

I've had the same problem since at least the introduction of Catalina. Sometimes SafeBoot fixes it but then it begins slowing again.

Have you tried rebuilding the mailboxes?
Simply done, go to 'mailbox' in the address bar and at the bottom of the list you'll find rebuid.
It can solve a lot of problems.
I have no idea what the red badge is by the way. i've never seen that that I can remember

Ruggy said:

Have you tried rebuilding the mailboxes?
Simply done, go to 'mailbox' in the address bar and at the bottom of the list you'll find rebuid.
It can solve a lot of problems.
I have no idea what the red badge is by the way. i've never seen that that I can remember

Thanks for your response/suggestion! Unfortunately, I have tried rebuilding all the mailboxes. Didn’t make the problem go away.

By the “red badge”, I mean the red circle on the Mail Dock icon that displays the number of unread messages inside of it.

Sounds horrible.

Another thing you could try, as long as you don't have any messages or folders stored under "On My Mac", would be to delete the accounts, delete everything in ~/Library/Mail, re-add the accounts and let all of your email and folders re-populate from the servers. The thinking here is that perhaps something in your Mail database has been corrupted and Catalina's version of Mail is choking on it.

Silverstring said:

Thanks for your response/suggestion! Unfortunately, I have tried rebuilding all the mailboxes. Didn’t make the problem go away.

By the “red badge”, I mean the red circle on the Mail Dock icon that displays the number of unread messages inside of it.

Ok got it thanks.
I would recommend you download another email client like Spark and see if you have the same problem.
If it's a problem with mail it will go away. If it isn't then it isn't mail so you've reduced the places to look.

I have had similar issues in the past. I removed my accounts from System Preferences > Accounts. Then started mail and added the accounts again.

BrianBaughn said:

Sounds horrible.

Another thing you could try, as long as you don't have any messages or folders stored under "On My Mac", would be to delete the accounts, delete everything in ~/Library/Mail, re-add the accounts and let all of your email and folders re-populate from the servers. The thinking here is that perhaps something in your Mail database has been corrupted and Catalina's version of Mail is choking on it.

I'll try this! Thanks for suggesting.

Silverstring said:

I'll try this! Thanks for suggesting.

This fix seemed to work for me ... or at least it's not as bad as it has been at times. As did deleting the Properties.plist file regularly.

I've tried all these approaches for Mac Mail 14.0 on my MacBook Pro, iPad Pro, and iPhone 11 Pro Max, but they still show ghost unread messages from Gmail on all three devices throughout the past year (on earlier versions of Mail and the current Big Sur version). Mail 14.0 will not update the content in any smart mailbox, even after a day of waiting.

I reformatted my SSD, installed Big Sur from a thumb drive, restored content from a new Carbon Copy Cloner backup, etc., but Mail will not update. You have the choice of only whichever smart folder you've clicked on after launching the application, and after that, the content remains the same, regardless of which other smart folders are clicked. I don't mean a lag; I mean it's permanent for the entire day.

I've downloaded and installed Spark, which I've being using on my iPad and iPhone for more than a year to avoid the distraction of those ghost badge counts. Now, with Mail not even displaying different content for different smart folders, I'm going to stick with Spark for my Mac as well.

Unresponsiveness of Apple native applications also led me to discontinue my Apple Music subscription in favour of a Spotify subscription because iTunes and later Apple Music would bring the computer (16 GB RAM and 2 TB SSD) to a standstill for hours, just short of freezing/hanging the system but not quite. Photos did that for a while, but it was just updating its database probably, and then it launches fine afterwards. That is never true of Apple Music, and now, it's no longer true of Apple Mail. Save yourself some agony by switching to Spark. If Apple never bothered to make iTunes and Apple Music usable, it's not likely to make Apple Mail usable either.

Ruggy said:

Ok got it thanks.
I would recommend you download another email client like Spark and see if you have the same problem.
If it's a problem with mail it will go away. If it isn't then it isn't mail so you've reduced the places to look.

Spark is lightning fast. I used it years ago, but it's much faster now. Had forgotten about it until reading this thread. I'm switching to Spark and saying bye bye to Apple Mail which is sluggish, slow and sad on OS Monterey.