I have my own Mailhosting, and am moving servers. Thunderbird works fine with the new Server IP. However, Apple Mail seems to fail and to silently ignore the new server.
I am using Courier IMAP and watching its log messages. When Thunderbird connects, I can see the successfull login. Apple Mail's activity window and network window shows a lot of stuff as well, but Courier keeps silent. Apple Mail then complains that it cannot connect. This is the only message I get in Apple Mail regarding the IMAP connection:
INITIATING CONNECTION Dec 28 18:15:53.727 [kCFStreamSocketSecurityLevelNone] -- host:myhostname.com -- port:143 -- socket:0x6000004c4210 -- thread:0x600000666340
For some reason, the connection is never mentioned again, and the signal in the network diagnosis goes "red" very quickly.
Any ideas what Mail is doing differently, compared to Thunderbird?