Re: Multiple message-ids.

Dave Crocker writes:
> So, Community, I'm querrying you:
>
>    Do you see multiple message-id's in messages?

Yes, but very seldom. On the order of once per million messages.

>    If you do, what affect do they have?

There are two varieties.

Sometimes I've seen repeated message-id fields. The exact same ID 
specified twice in the header of the same message. No effect.

Messages with two different message-ids also occur. In the real examples 
I've seen, both IDs were usually added in the same administrative 
domain, although sometimes I wasn't sure of that. This has little or no 
effect. More MUAs construct References from the first ID than from the 
second.

I've never seen a message with more than two Message-ID fields in the 
same header.

All this based on my corpus and YMMV and have a pleasant Sunday.

Arnt