Re: MTA

[Vincent Lefevre <vincent@vinc17.net>]

On 2021-07-05 09:35:22 -0400, Greg Wooledge wrote:
[...]
> Your "reverse" (PTR record for 162.213.253.79) doesn't match.  Which is
> to say, none of the "A" results from cyrania.com. match the original
> IP address of 162.213.253.79.
> 
> Some SMTP receivers may care about that.
[...]

Yes, the reason is that the owner of the IP address can technically
put anything for the reverse, in particular a domain he doesn't own.
Thus he can put a domain with a good reputation to send spam. That's
why antispam software should check that the reverse resolves back to
the IP address.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)