I switched to mailgun after mandrell went away as suggested in discourse. However, now all of my emails sent to comcast.net email addresses are failing with: “550 5.1.0 Invalid sender domain”. It works for every non comcast customer though.
This obviously isn’t an issue with discourse, but I was hoping someone might have some insight. I called comcast and they were completely useless and have opened a ticket with Rackspace. We will see what they say. In the meantime…
Thanks for any help!
I figured it out. I thought I would document it here in case anyone else needs help in the future.
The sender of the email was coming across at comcast as ‘xx@mg.mydomain.com’, which comcast was trying to verify.
I needed an additional MX record. I use Google Apps for normal emails, but also Mailgun. I had all the Google Apps MX records, but what I had to do was add an additional MX record with a subdomain of “mg” for mailgun, which I just pointed at google server. Here are my MX records, which seem to now be working:
MX Records
Mail Server Preference Subdomain TTL
aspmx.l.google.com 1 Default
alt1.aspmx.l.google.com 5 Default
alt2.aspmx.l.google.com 5 Default
alt3.aspmx.l.google.com 10 Default
alt4.aspmx.l.google.com 10 Default
aspmx.l.google.com 20 mg Defaultمرحبًا، شكرًا لك يا صديقي! واجهتُ نفس المشكلة اليوم مع مستخدم من Comcast وخدمة Mailgun. الآن يجب أن أجد أفضل طريقة للتعامل مع سجلات MX.
أردت أيضًا التعبير عن امتناني لمشاركة الإجابة هنا! كان الإصلاح سهلاً.