On 12 Mar 2019, at 12.04, Joe Wong via dovecot <dovecot@dovecot.org> wrote:

Hello,

 I have defined the following:

mail_location = maildir:~:INBOX=~/Maildir:LAYOUT=fs:INDEX=%u

%u is retrieve via database in that my username contain ":", in which it create some confusion to dovecot:

doveadm index -u user1:site@domain iNBOX
doveadm(user1:site@domain): Error: remote(192.168.10.22:24245): Namespace '': Unknown setting: site@domain

I cannot change the value in DB so is there a workaround to this problem?

Convert the username to not have ':' when it comes out of auth. Could be possible with SQL userdb. With others .. I'm not sure, you might have to use Lua to convert it.