The SAFEST return address for probes of that type would be a
null sender <>, simply by virtue of it not generating a
reply. However, some very misguided postmasters block support
for null senders, which also effectively blocks bounce
messages, without having any real impact on blocking spam.
They are using a null from first, ie. <>, and if they receive a 500-series
error after the 'mail from:' command or after the 'rcpt to:' command, they
issue a 'rset' (reset) and issue 'mail from:
antispam******(_at_)west(_dot_)verizon(_dot_)net', the asterisks representing a
string of six
random numbers. They setup a wildcard account for west.verizon.net on the
mail system in case the remote host performs Sender Verifications checks.
-Dennis "Used to work for Verizon abuse" Dayman
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