Hello all, RFC3501 describes among other things that custom flags can be set for mails. These can be allowed or forbidden in the server: "Servers MAY permit the client to define new keywords in the mailbox".

When I am on our server, it also looks like dovecot basically allows this:

a select INBOX FLAGS (\Answered \Flagged \Deleted \Seen \Draft $Forwarded Old $ITipAnalyzed $ITipProcessed Forwarded NonJunk $cl_1 $cl_2 $cl_3) OK [PERMANENTFLAGS (\Answered \Flagged \Deleted \Seen \Draft $Forwarded Old $ITipAnalyzed $ITipProcessed Forwarded NonJunk $cl_1 $cl_2 $cl_3 \*)] Flags permitted.

The only option that goes in this direction is this one:

mail_max_keyword_length

But basically describes something else as well, if I see it correctly.

Is there a way to prevent dovecot from giving custom flags, or what is the name of the parameter where you can set this?

Best