Set sendgrid Incoming Mail Parse webhook

Question

I'm using gmail MX for outgoing mail. i.e. I have 5 MX record with gmail. Now I want to use sendgrid incoming mail webhook for parsing replied mails. For this, I'm using griddler.

My queries are,

1. what will happen if my DNS have two different MX record with same priority (i.e. I have 5 entry for gmail MX, and 1 for sendgrid as described in documentation.)

2. Will any existing functionality break? Is this the right way to setup ?

   MX exmaple.com 3600 xyz.google.com (P: 5)
   MX exmaple.com 3600 abc.google.com (P: 5)
   MX exmaple.com 3600 sdmx2.googlemail.com (P: 10)
   MX exmaple.com 3600 asdpmx3.googlemail.com (P: 10)
   MX exmaple.com 3600 asdpmx.l.google.com (P: 1)

   MX exmaple.com mx.sendgrid.net (P:1) <----

Thanks.

Answer 1

If you put SendGrid at the highest priority, it will effectively take all the mail, and none would go to Google. That's why SendGrid strongly recommends you use a subdomain for Parsing, not your main domain.

Answer 2

Multiple MX entries shouldn't be a problem if you use a subdomain. We have a MX like : MX email.example.com mx.sendgrid.net (P:1) and the parsing works fine (great I must say).

If you don't want to use a subdomain, I think you're bound to put sendgrid at the highest priority and it shouldn't affect the existing entries.