Monday, March 10, 2014

How we resolved email delivery issue when MX record got ignored by some mail servers?



We had a strange email delivery issue, some emails to our corporate email account where not getting delivered when sent from some email domains. Some of them who faced the issue called us when they didn't get a reply for their emails. We don't want this to happen with our clients or prospects who are trying to contact us. As being a technology company we could not allow this to happen and took it up as challenge that we needed to fix ASAP.

We have our static site running on Amazon S3 and have set up a CNAME record to cover the domain so that we can have the URL of http://mydomain.com (note that I am replacing our real domain with mydomain.com throughout this).  Request coming to http://www.mydomain.com was redirected to http://mydomain.com.

The issue is that sometimes when an email send to info@mydomain.com, the domain part gets replaced with s3-website-ap-southeast-1.amazonaws.com during the domain name resolution process.