OGo can use Postfix to deliver mail. In the case that you want to deliver to a password protected host (eg using 1&1), you need to properly configure postfix ...

Many thanks go to Torsten Becker for posting the solution on users-de!

The Issue ...

OGo itself does not use the SMTP protocol itself, but rather uses the local mail system. So how does one make the local MTA use "authenticated SMTP" to the next mail-host (relay host) - eg, if your provider requires SMTP authentication.

The solution ...

Tested with Postfix-1.11.xx on Debian.

To make Postfix use "Authenticated SMTP" one needs the postfix-tls package. Included are example scripts on how to use authentication during sends as well as during receives.

For sending mail the following entries in the main.cfg of Postfix are valid:

# SMTP CLIENT CONTROLS
# The smtp_sasl_auth_enable parameter controls whether authentication
# is enabled in the Postfix SMTP client. By default, the Postfix SMTP
# client uses no authentication.
#
#smtp_sasl_auth_enable = yes
smtp_sasl_auth_enable = yes
# The smtp_sasl_password_maps parameter specifies the names of lookup
# tables with one username:password entry per remote hostname or
# domain. If a remote host or domain has no username:password entry,
# then the Postfix SMTP client will not attempt to authenticate to
# the remote host.
#
# The Postfix SMTP client opens the lookup table before going to
# chroot jail, so you can leave the password file in /etc/postfix.
#
smtp_sasl_password_maps = hash:/etc/postfix/saslpass
...
# By default, the Postfix SMTP client will not use plaintext passwords.
#
#smtp_sasl_security_options =
smtp_sasl_security_options = noanonymous

As noted above, you need to configure the proper password in /etc/postfix/saslpass.

This is required by anyone who intends to send mail using 1&1 (a German Internet provider).