Re: Have message-ID set by my email server rather than by Message

[rameiko87]

Dear Lars-Johan Liman,
Thank you very much for your kind and exhaustive reply. I read in the 
Gnus manual:

> If you have no idea what to insert for "yourmachine.yourdomain.tld", 
> you’ve got several choices. You can either ask your provider if he 
> allows you to use something like yourUserName.userfqdn.provider.net, or 
> you can use somethingUnique.yourdomain.tld if you own the domain 
> yourdomain.tld, or you can register at a service which gives private 
> users a FQDN for free.

None of these apply to me. Then I read just below:

> Finally you can tell Gnus not to generate a Message-ID for News at all 
> (and letting the server do the job) [...] you can also tell Gnus not to 
> generate Message-IDs for mail by saying:
>
> //there's some code here//
>
> , however some mail servers don’t generate proper Message-IDs, too, so 
> test if your Mail Server behaves correctly by sending yourself a Mail 
> and looking at the Message-ID.

This is perfect! So I customized message-required-mail-headers. Now your 
explanation shows why I should not remove the mail headers, but still I 
wonder about the meaning of the lines cited above from the Gnus manual. 
And I also wonder what is the meaning of the variable 
message-required-mail-headers if it's essentially ignored by Message 
when I remove the Message-ID header from the list.

Anyway now I'm back to the original problem where I don't know what to 
insert for Message-ID because the recommendations from the Gnus manual 
above don't apply, and also I can't understand how Message generates the 
portion which comes before the at-sign...

And by the way, the standard for me would be 
fedora.mail-host-address-is-not-set . Is this even a fully qualified 
domain name, without extension? And how would I set mail host address? 
Because I can only find the variable mail-host-address which is set to 
system-name, which is fedora. Therefore I would expect the Message-ID to 
be fsfxxxxxxx@fedora
(which by the way I think would miss the extension). If I set 
mail-host-address manually to fedora.ext, would Message-ID then be 
fsfxxxxxxx@fedora.ext? Then why don't they say 
mail-host-extension-is-not-set rather than mail-host-address-is-not-set 
in the default Message-ID when the mail-host-address *is* set but has no 
extension? So much confusion.

On 09.12.2023 08:03, Lars-Johan Liman wrote:
> Hi!
>
> Message-ID is one of the very few _mandatory_ header lines, so a 
> message
> without one is not a valid RFC 5322 (the sucessor of RFC 822) message.
> Therefore the message "must not/cannot" leave your computer without 
> one.
> It has to be set on the computer if it's being shipped by a 
> mail-related
> protocol ((E)SMTP/LMTP/IMAP/POP[23]/...).
>
> What you _can_ do (if I remember my sendmail.cf right, it's been a few
> years since I taught that course ... ;-) ) is to _modify_ the 
> Message-ID
> header in your mail server. "If it looks like it's coming from the
> computer, then modify Message-ID to look like ... (bla)". But I 
> wouldn't
> recommend it. Message-ID is supposed to be set by the sending software
> (the Mail User Agent (MUA)) and it's supposed to uniquely identify the
> message across all messages in the world ... ever. Modifying it would
> make it very difficult to trace and debug how the message traverses the
> Internet (which includes your computer). You can probably also 
> influence
> exactly how Emacs generates the Message-ID, but again, it's probably 
> not
> a good idea to mess with that.
>
> Can I ask what problem you see with having your Emacs generate the
> Message-ID?
>
>                                 Best regards,
>                                   /Lars-Johan Liman