Re: Who should set the Sender: header field?

--On Thursday, December 16, 2021 21:30 -0500 John R Levine
<[email protected]> wrote:

> On Thu, 16 Dec 2021, John C Klensin wrote:
>> When that new way of doing things will break the multiple From
>> option, mess up mailing lists (although people are welcome to
>> use their various group and social network services instead),
>> ...
> 
> I'm with you on mailing lists, but the support for multiple
> From is spotty even outside of gorilla land.  I sent myself a
> message with a two-address From header and found that the mail
> app on my Samsung phone and Apples iPad mail showed only the
> first address, Apple mail and Thunderbird on a Mac showed both.
> 
> I'm not sure what to say about it but we are doing people no
> favors by suggesting that mail with multiple from address is
> likely to work.

I would favor a statement in the proposed A/S about this (or any
similar feature) warning people that the feature is not widely
supported, that it cannot be expected to work universally in an
interoperable way, may result in mail being bounced and/or lost,
and hence should probably be avoided unless the sender knows it
will be handled properly at the recipient end.  I'd be hesitant
about removing the construction from 5322bis entirely, but could
be convinced.

The _only_ thing is would object to is arguing that the standard
must be changed because one or several perceived large Gorillas
have decided to not support it.

  best,
   john