deoren:
> Hi,
>
> I searched via Google and via the mailing list archives, but I didn't
> find a post which matched my specific situation.
>
> I see those warnings in the logs when the system goes down for a reboot.
What warnings? You failed to include the program name. As the system
shuts down, it kills processes.
> Is the mail lost? Should I be using a different approach when rebooting
> a server running Postfix? Does the client receive an error and it's then
> up to it to try again?
As required by the SMTP standard, the Postfix SMTP server does not
report success at end-of-data before the message has been stored
(in the case of UNIX-like systems, that includes an fsync call on
the queue file handle).
The same logic applies for local submission and other message
handling paths. The Postfix sendmail command will report "success"
(exit status zero) only after the message is stored. Otherwise, the
program that invokes the Postfix sendmail will have to deal with
the error (as expressed with the exit status);
Wietse
