On Wed, 27 Jul 2016 11:16:21 PM Richard James Salts wrote: > On Wed, 27 Jul 2016 12:50:59 PM Viktor Dukhovni wrote: > > On Tue, Jul 26, 2016 at 05:34:34PM -0700, Mike Kadin wrote: > > > help.uber.com is a CNAME to frontends.uber.com which is a CNAME to > > > frontends-sjc1.uber.com which has an MX record of mx.sendgrid.net. > > > Sendgrid is our inbound SMTP provider: > > > ... > > > help.uber.com. 60 IN CNAME frontends.uber.com. > > > frontends.uber.com. 60 IN CNAME frontends-sjc1.uber.com. > > > frontends-sjc1.uber.com. 300 IN MX 0 mx.sendgrid.net. > > > ``` > > > Delivery Host: mx.sendgrid.net > > > Delivery IP: 167.89.125.4 > > > Size: 39.83 KB > > > Result: 25: SMTP error from remote mail server after RCPT TO:< > > > [email protected]>: 454 4.7.1 <[email protected]>: > > > Relay > > > access denied > > > ``` > > > > Note that the DSN code is "4.7.1", which is: > > https://tools.ietf.org/html/rfc3463 > > > > X.7.1 Delivery not authorized, message refused > > > > The sender is not authorized to send to the destination. This > > can be the result of per-host or per-recipient filtering. This > > memo does not discuss the merits of any such filtering, but > > provides a mechanism to report such. This is useful only as a > > permanent error. > > > > When I send a probe to <[email protected]>, I get: > > Reporting-MTA: dns; mournblade.imrryr.org > > X-Postfix-Queue-ID: 23C8D284F25 > > X-Postfix-Sender: rfc822; [email protected] > > Arrival-Date: Wed, 27 Jul 2016 12:46:05 +0000 (UTC) > > > > Final-Recipient: rfc822; [email protected] > > Original-Recipient: rfc822;[email protected] > > Action: deliverable > > Status: 2.1.5 > > Remote-MTA: dns; mx.sendgrid.net > > Diagnostic-Code: smtp; 250 2.1.5 Ok > > > > So the issue sure looks like sendgrid is blocking the sending host, > > envelope sender domain, or specific recipient address. > > This is because postfix and exim differ on where the mail should be sent. > http://cr.yp.to/im/cname.html explains the problem: sendmail accepts a > domain with a CNAME record. It replaces the domain with the CNAME value > before using it in RCPT, unless it is acting as a dumb client. Similar > comments apply to qmail and other mailers.
From all the documentation I can see exim doesn't do this by default, maybe this site has implemented it in their routers as a backwards compatibility step with sendmail. -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
