Maximum MX records and UDP

Today I have received an interesting question.  Coming from an Exchange background I thought it might be a Lotus specific item and of course stated I had no answer to this question.

Now, that said let’s see some of your thoughts on this question:

“What is the maximum number of MX records you can have?”

Here is my thought on this:
Honestly there is a theoretical limit of 10 in IPv4 and a payload of 65507 bytes where IPv6 is 65527 bytes.  Anything larger results in IP fragmentation; definitely bad for email.  That said why would you do more than 4-5 MX records to begin with?  That is a theoretical limit, not an actual published limit.

It has definitely lead to many internal interesting discussions today with several other engineers.

Batter up!!

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