Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

header field repetition

11 views
Skip to first unread message

Adrien

unread,
Jan 5, 2011, 12:05:24 PM1/5/11
to
Hi,

I would like to know if field repetition are still valid in email
headers.
I have found an old note in RFC-822 (http://tools.ietf.org/html/
rfc822#section-4.1) about this being discouraged:

"This specification permits multiple occurrences of most
fields. Except as noted, their interpretation is not
specified here, and their use is discouraged."

Do you know if there is any update about this.
More precisely I would like to know if fields "From:", "To:" and
"Subject:" are allowed to be present multiple times in a mail
header ?

Thanks!

Adrien

unread,
Jan 5, 2011, 1:59:00 PM1/5/11
to
On 5 jan, 18:05, Adrien <adrien.sala...@gmail.com> wrote:
> Hi,
>
> I would like to know if field repetition are still valid in email
> headers.

I have found the answer in rfc 2822: these fields can only be present
0 or 1 time for subject and to, and 1 time for From.


David F. Skoll

unread,
Jan 5, 2011, 4:28:58 PM1/5/11
to
Adrien wrote:

> More precisely I would like to know if fields "From:", "To:" and
> "Subject:" are allowed to be present multiple times in a mail
> header ?

There's a nice table in RFC 5322 that shows the minimum and maximum
allowed counts for various headers.

Specifically, From: must appear exactly once, and To: and Subject:
can appear once or zero times.

(I don't think RFC 5322 is actually the standard just yet, but
it probably will be at some point.)

Regards,

David.

Jorgen Grahn

unread,
Jan 5, 2011, 6:20:36 PM1/5/11
to

Good, but keep in mind that whatever the RFCs say, you have to decide
what to if they appear multiple times, and "ignore/reject the mail" is
most likely not the right answer.

/Jorgen

--
// Jorgen Grahn <grahn@ Oo o. . .
\X/ snipabacken.se> O o .

0 new messages