Absolutely not! It would have had greater effect if it read (and I work without context):
Your boss doesn't appear to appreciate the requirements of operating an SMTP relay. Consider an ASA or something, and also consider finding a new job if you're being put in situations like this.
The cumulative effect of the comment as quoted by Iain is such that it has no redeeming merit and the flag should have been accepted; it is not a constructive or professional comment even in our profession.