Maybe they are blocking your /24?
Do me a favor, try going one step further. It accepts me during my test as a from, but as soon as I give it the rcpt to, it says I can't send to it.
this is a telnet log of an attempt (I also tried it using the specific rdns for the IP as resolved, so see if it was just being really really picky about a match)
220 oe-mp1.bizmailsrvcs.net ESMTP server (InterMail vM.5.01.06.05 201-253-122-13
Oh look, a Verizon mail server.
Verizon (which uses the bizmailsrvcs.net domain name) runs some very bad filtering on their inbound mail. One thing they do is to test MAIL FROM parameters for legitimacy by seeing if they can get through the RCPT phase of trying to mail to them. The effect of this is that if you are using something that would reject mail from the Verizon test machines, you can't mail anyone using a Verizon mail server.
-- Bill Cole [EMAIL PROTECTED]
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