From: ned(_dot_)freed(_at_)mrochek(_dot_)com
Subject: Re: limitation of the number of To: (and Cc:)
Not necessarily; the agent is free to combine all the To: addresses
into a single To: field and all the Cc: addresses into a single Cc: field.
The user agents I am familiar with do this.
The background of my question: my mail reader doesn't combile
addresses even if there are multiple To: fields. I think this is
conformant to RFC822.
Well, sort of. It says:
This specification permits multiple occurrences of most
fields. Except as noted, their interpretation is not
specified here, and their use is discouraged.
Reading RFC2822, I realized that I should modify my mail reader to
combine addresses to a single To: field as you said, Ned.
I'd recommend it.
I needed to know why RFC2822 made such a change before implementing
it.
That's a somewhat different question than what you asked before. I believe the
answer is that since RFC 822 allowed multiple fields but didn't specify their
semantics, we've ended up with different and incompatible behavior in different
implementations. But one of the things we have to do when revising
specifications is to clear up ambiguities that lead to interoperability
problems. Failure to do so would lead to the specification not meeting the
requirements for standards track advancement.
Personally, I feel that this requirement of RFC2822 should have be a
"SHOULD", not a "MUST".
A SHOULD would not have solved the interoperability problem. The viable choices
here were to either allow multiple fields and require them to be handled in a
fashion that's no different than a single field or disallow multiple fields.
Given that RFC 822 discouraged the use of multiple fields it seems clear that
the latter is the way to go.
Ned