Apple Mail Randomly Takes Account Offline, and Can't Reconnect

I have noticed that the Mail app will occasionally be unable to connect to my zimbra based mail server. This has happened several times in the past, and is happening to me currently, and so I am taking the opportunity to try to ask others for help.

Here are the symptoms/steps I have taken:

1. I see a warning triangle next to the Inbox label

2. In the mail connection doctor, I see

2. In the logs, I see

INITIATING CONNECTION Oct 28 09:26:20.977 host:<mail-server> -- port:993 -- socket:0x0 -- thread:0x60800007b600

INITIATING CONNECTION Oct 28 09:26:20.978 host:<mail-server> -- port:465 -- socket:0x0 -- thread:0x610000a6f9c0

3. In the menu bar Mailbox menu, and by right-clicking the warning triangle I have tried Take all accounts online, Get New Mail, and Synchronize <account>

4. I have tried to Quit, then restart Mail

5. I just now made a non-recursive copy of ~/Library/Mail/V2/MailData/* to see if anything changes when I restart.