Horde Kronolith event invitations SMTP configuration

Horde is pretty confusing to begin with. When using Kronolith (Calendar) to send out event invitations, Kronolith doesn't use the information in /usr/local/cpanel/base/horde/config/conf.php to send out mail. Instead it tries to connect to 127.0.0.1 on port 25 and send out unauthenticated mails. It does not attempt to use SMTP Authentication. If you have /usr/local/cpanel/base/horde/config/conf.php set to use port 587 for sending out mail, it does not use that. Steps to reproduce Log into Horde Webmail account Select New Event from Calendar Add some email addresses in the Attendees tab Save Send updates to attendees? Select Yes [plain]There was an error sending an event notification to xxxx@xxxx.com: Failed to set sender: yyyy@yyyyyy.com [SMTP: Failed to write to socket: not connected (code: -1, response: )][/plain] Sending mail out through the Mail application in Horde works fine and as expected (through port 587 using the logged in credentials for SMTP Auth). But Kronolith - and perhaps other Horde Applications, do not. There's a really old discussion about this on the Horde Mailing List: