Configuration » Remote Server Settings: Common NNTP POP3 SMTP
Authentication required (SMTP AUTH)
If marked, SMTP's AUTH command is used to login to this SMTP server.
SASL mechanisms to be used for authentication
Defines a list of SASL mechanisms (separated by space), which may be used to
login on this server. An empty setting means, that all supported mechanisms may
be used.
Currently supported are: DIGEST-MD5 CRAM-SHA1 CRAM-MD5 PLAIN LOGIN