[imp] Horde webmail, FreeBSD, Imap or Smtp server outgoing authentication error

[David Mehler]

Hello,

 I've got a new horde webmail install going on a FreeBSD 11.1 jail.
 I've got Dovecot set up so that it appends a domain name if one is not
 given, so that user and user at example.com can both log in. The Dovecot
server handles imap authentication as well as smtp authentication from
postfix. Dovecot in turn gets its authentication via a MySQL database.

 When I logged in with horde webmail I used for the first attempt
 username with no @example.com suffix. I logged in ok, but couldn't
 send an email, gave me a weird error no address associated with host.
 I logged out, logged back in using user at example.com the full address,
 and this time the message sending went through.

I could provide Dovecot, Postfix, and/or Horde Webmail configurations,
but didn't want to include them all without knowing where this issue
most likely resided. If it matters the web server is Apache 2.4.

Thanks.
Dave.