Mail best practices?

Tue Sep 3 21:58:25 UTC 2013

Without going to a dedicated list for something like this, I'm looking for a
common sense approach.

Sep  3 17:55:20 XXX sendmail[155]: r83Lse37000155: rejecting commands from
outmail016.ash2.facebook.com [66.220.155.150] due to pre-greeting traffic

Sep  3 17:55:22 XXX sendmail[156]: r83Lsg6N000156: rejecting commands from
outmail015.ash2.facebook.com [66.220.155.149] due to pre-greeting traffic

Isn't this sort of thing supposed to be frowned upon still? I am not trying
to name & shame here, but I figured this is a pretty big/respectable email
sender.

Thoughts for balancing sensible network spam management with sensible best
practices that affect lots of users?

Thanks in advance,

Deepak