Re: Test email errors

Hello again George,

On Fri, 5 Jun 2026, [email protected] wrote:

> I've potentially made some progress.

:)

> ... sendmail had never been installed so that has been done now.

In your OP you'd said that you installed msmtp as an MTA in preference
to Sendmail because of its simpler configuration.  But never mind that
now, you seem to have moved things on quite a way. :)

> It's running as a service fine but reporting various errors about
> unqualified host names.  I don't suppose this is really surprising
> because I haven't configured sendmail.

Sendmail needs to know who it's working for - its domain.  Usually you
would configure it to route mail for just one domain.  Large providers
will handle mail for millions of domains.  Sendmail can be picky about
the domains it will do work for, I'll mention that later.

> Running the test message command under su backuppc now completes without
> flagging any errors.  Unfortunately, though, the email doesn't get sent
> and the mail is returned reporting authentication failures.  e.g.
>
>    ----- The following addresses had permanent fatal errors -----
> <|[email protected]|>
>     (reason: 550 Authentication is required for relay)
>
>    ----- Transcript of session follows -----
> ... while talking to mail5.hostinguk.net.:
>>>> AUTH dialogue
> <<< 535 Authentication failed
>>>> MAIL From:<|[email protected]|> SIZE=527
> <<< 550 Authentication is required for relay
> 554 5.0.0 Service unavailable
>
> Again, this may be because I haven't configured sendmail.  But I have
> configured msmtp and it works correctly from my normal user account.

This doesn't look to me like a Sendmail configuration problem.  This is
what for example Sendmail does when it's being picky. [*]  It's what I
would expect to see if for example you were a criminal, trying to send
spam through somebody else's mail server.  It doesn't matter whether or
not the mail server is running Sendmail.  Any (sane) MTA will refuse to
do what you seem to have asked it to do there.

Is hostinguk.net your email service provider?  If so then presumably
when you send your own mail through their service you have to give to
the service provider some "AUTH" information before they will let you
send the mail.  That information will only be valid for the address or
addresses for which they have agreed to send mail.  The '550' response
(refusal) that you received from your provider I think means that you
have tried to do something that hasn't been agreed with them.

Do you really want to send mail from the BackupPC server through your
email provider?  If you do, I guess it might be OK *if* the recipient
address is in the same domain as your sending address.  Personally I'd
keep this sort of mail entirely inside the local network if possible.

[*] Normally Sendmail will refuse to 'relay' mail.  That means accept
mail to a non-local domain from a non-local domain and simply send it
on.  Unless you really know what you're doing it is a VERY BAD IDEA to
relay mail on a server exposed to the Internet, because then criminals
will (soon) find the 'open proxy' server and use it for their criminal
purposes.  Later on, your service provider would probably explain that
its reserves of patience are limited.

-- 

73,
Ged.


_______________________________________________
BackupPC-users mailing list
[email protected]
List:    https://lists.sourceforge.net/lists/listinfo/backuppc-users
Wiki:    https://github.com/backuppc/backuppc/wiki
Project: https://backuppc.github.io/backuppc/