Incorrect SSL returned by Dovecot when connecting using an addon domain or subdomain

Symptoms

An addon domain or subdomain's SSL certificate is not returned by the Dovecot service when making an IMAP or POP3 connection.

Description 

Dovecot uses the /etc/dovecot/sni.conf for the SSL configuration. The domain will not be added to the configuration if there are no email accounts.

Workaround

Create an email address to the addon domain or subdomain:

How can I create an email account?

After, rebuild the Dovecot SNI configuration:

/scripts/build_mail_sni --rebuild_dovecot_sni_conf

/scripts/restartsrv_dovecot