John R Pierce wrote:
Christopher Chan wrote:
configure your sendmail to use your ISP's mail server as a 'smarthost'.
How is that going to help the dest mta verify his address?
it won't have to. his ISP will accept mail from its own customer's IP address, same as if they were end user mail clients, and it will relay for him. the destination MTA will presumably accept mail from his ISP's mail server, unless they are a known spammer.
The dest mta is most probably doing a blank sender address verify on all emails. Although running a mail server on a dynamic ip is discouraged and use of the ISP's relay box is encouraged, I doubt that in this case that it will make any difference unless the dest mta has the ISP's ip(s) whitelisted which I doubt every much. The solution is to use a verifiable returnpath with bonus points for setting DS.