mech_list
Whitespace separated list of mechanisms to allow (e.g. plain anonymous). Used to restrict the mechanisms to a subset of the installed plugins. (default: use all available plugins)
Used with Cyrus SASL version 2.x.x.
With Cyrus SASL version 1.x.x your only choice is to delete the corresponding
library files from the SASL plug-in directory.
Possible values:
plain
login
digest-md5
cram-md5
anonymous
kerberos_v4
gssapi
otp
external