[Mailman-Users] why i must use DELIVED_MOD="Sendmail" but cannot use DELIVED_MOD="SMTPdirect"?

[mobo]

Hi, everyone.
 When i use DELIVED_MOD="SMTPdirect" in Mailman/Defaults.py and I cannot use sendmail to 
send mail. It seemd that I must use DELIVED_MOD="Sendmail", mailman can let me send mail 
with sendmail.
 But i know the Sendmaildirect MOD is not enough safe. Can i change something to use SMTPdirect MOD instead of Sendmail MOD.
THANKS.