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. -- ## 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/
