Mike - Rants - Technical

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!!

One comment on “Maximum MX records and UDP

Comments are closed.