> From: Russell Robinson
> I've got:
> require verify = sender
> Recently tested: it always succeeds - i.e. allows invalid senders.
"verify=sender" checks domain only. If it allows invalid domains
then either an "accept" succeeded before this "require" or
blame the NS you use.
An attempt to check existence of a mailbox (i.e. to check whole
email address, not only domain) requires connection with the MX
and giving HELO, MAIL, RCPT commands - that is called "callout" in Exim.
Callouts to each sender is considered abuse and can cause you blacklisted.
