Updating:
args = username_format=%Ln
under userdb did not fix my issue.
My server still rejects incoming emails with uppercase username e.g. USERNAME@tld.
In /etc/dovecot/conf.d/auth-passwd-file.conf.ext, before I updated with your suggestion i.e. %Ln, I had:
passdb { driver = passwd-file args = scheme=CRYPT username_format=%u /etc/dovecot/users }
userdb { driver = passwd-file args = username_format=%u /etc/dovecot/users
I updated to
passdb { driver = passwd-file args = scheme=CRYPT username_format=%u /etc/dovecot/users }
userdb { driver = passwd-file args = username_format=%Ln /etc/dovecot/users
FYI after I updated and tested sending an email with uppercase username again, I ran
# systemctl reload dovecot postfix
also
# dovecot reload
What else can I try?
I tried args = username_format=%Lu too, in vain.
PS thanks for pointing that I should look at username_format rather than auth_ username_format
# dovecot -n # 2.3.7.2 (3c910f64b): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.7.2 () # OS: Linux 5.4.0-156-generic x86_64 Trisquel GNU/Linux 10.0.1, Nabia # Hostname: mail.redacted_tld auth_mechanisms = plain login auth_username_format = %n mail_location = maildir:~/Maildir mail_privileged_group = mail namespace inbox { inbox = yes location = mailbox Drafts { auto = create special_use = \Drafts } mailbox Junk { auto = create autoexpunge = 30 days special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox Trash { auto = create special_use = \Trash } prefix = } passdb { driver = pam } protocols = imap lmtp imap lmtp service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } } service lmtp { unix_listener /var/spool/postfix/private/dovecot-lmtp { group = postfix mode = 0600 user = postfix } } ssl = required ssl_cert = </etc/letsencrypt/live/mail.redacted_tld/fullchain.pem ssl_client_ca_dir = /etc/ssl/certs ssl_dh = # hidden, use -P to show it ssl_key = # hidden, use -P to show it ssl_min_protocol = TLSv1.2 ssl_prefer_server_ciphers = yes userdb { driver = passwd }