Am 19.12.2011 02:15, schrieb Steve Fatula: > Steve Fatula: > > Have not seen a discussion of this lately, I'd like to hear pros > > of disallowing said spoofing. It appears it's "allowed" in the > > SMTP "standard". So, are there reasons to not allow it? > > You mean, forbid mailing list postings (like yours), because they > arrive from outside, but have a sender address inside the network? > > No, speaking of sending email. So, a postfix system where I might have a user > st...@domain.com, yet, send mail as > this yahoo address, both envelope and sender. I am not speaking of blocking > or checking incoming mail, talking > about essentially things like reject_sender_login_mismatch et al. While I > understand the intent of preventing this > when used by spammers, I can also understand that sometimes, it may be valid > to change the mail from. > > So, in general, what I am asking is what is the currently accepted best > practice (if any)? I see spf as the tool to > detect it, not my question. I am asking if mail systems could allow it, yet, > be good netcitizens.
a general rule for mail systems is do NOT send messages with senders you would not receive messages , so the answer is NO do not allow send with foreign domains and even not with non-existent addresses in xour local domains
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