I just created a subfolder in Apple mail. It shows up on the server as .list.Subfolder I drug your message into the folder, and the message shows up in Mail.app and shows up in the subfolder on the server
# ls -lnR .lists.Subfolder [10:40] [/usr/local/virtual/kremels@kreme.com/Maildir] total 56 drwx------ 2 89 89 512 Jul 11 10:41 cur -rw------- 1 89 89 21 Jul 11 10:41 dovecot-keywords -rw------- 1 89 89 109 Jul 11 10:41 dovecot-uidlist -rw------- 1 89 89 1924 Jul 11 10:41 dovecot.index.cache -rw------- 1 89 89 868 Jul 11 10:41 dovecot.index.log -rw------- 1 89 89 0 Jul 11 10:35 maildirfolder drwx------ 2 89 89 512 Jul 11 10:35 new drwx------ 2 89 89 512 Jul 11 10:41 tmp
I’ve created a test server and found out that the driving factor is what the namespace separator is set to. If set to /, Apple Mail gets confused and URL-encodes it when creating a new folder. If the separator is blank (as set by default) or set to e.g. a dot, everything works just fine.
Based on example and docs I found, a slash character should be good or even recommended, suggesting this is some kind of bug in Apple Mail, but I’m not versed enough in the IMAP related RFCs to understand.
This definitely used to work fine in the past.
Running 2.3.10.1 as part of the Mailcow suite.
I'm not familiar with that. Is that running dovecot on your Mac? My server is a FreeBSD 12.1 machine running dovecot-2.3.10.1_2.
Mailcow is a suite of server SW based on Dovecot & Postfix, intended to provide a full-featured mail server. In effect I’m running Dovecot in a Docker container on Alpine Linux.
-F