Scalable Mail Server

Paul Civati paul at
Thu Apr 14 16:49:45 BST 2005

Martin Hepworth <martinh at> wrote:

> if the MX records have the same value then it will round robin and when 
> one dies it will automatically just use the remaining ones.

Advisable, otherwise you can get into a tangle with tiered MX..

MX 10 A
MX 20 B
MX 30 C
MX 40 D

What I've seen happen with some MTAs is that when A becomes overloaded
then mail is obviously delivered to B, C, D..  problem here is that
queued mail on C/D then tries to redeliver and if A is still overloaded
ends up just one hop further down the MX tree at B/C, for no benefit
but more overloading.


Paul Civati <paul(at)> 0870 321 2855
Rack Sense Ltd - Managed/Business hosting -   
RackRed - Value SSL certificates and servers -

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