Hi folks, Uber users can initiate support tickets by replying to certain emails; the replies go to [email protected]. We've recently received a report from a user of EXIM that their emails were bouncing when sending to this domain.
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: ``` kadin-C02L70PZFLCG:~ mikekadin $ dig help.uber.com MX ; <<>> DiG 9.8.3-P1 <<>> help.uber.com MX ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13008 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;help.uber.com. IN MX ;; ANSWER SECTION: 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. ``` The user who reached out said that they are using Exim 4.87 and had the following results when sending a test email to [email protected]: ``` Recipient: [email protected] Router: dkim_lookuphost Transport: dkim_remote_smtp Out Time: Jul 21, 2016 1:13:13 PM ID: 1bQHXO-00020O-59 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 ``` Do you think Uber's DNS configuration for help.uber.com is problematic? Is this the expected behavior for Exim? Or is it possible that this Exim instance has some kind of configuration that could cause this? Thanks for your time, -- Mike Kadin [email protected] -- ## 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/
