rmail & sendmail

[kevin shell]

Hallo.

What rmail does before execve(2) sendmail?
What program generates these strings?
"From "
"remote from"
Why it's necessary to run rmail instead of directly running sendmail for uucp?

[Grant Taylor]

On 8/10/20 6:11 PM, kevin shell wrote:
> Hallo.

Hi,

> What rmail does before execve(2) sendmail?

I'm presuming that it extracts the necessary data to provide to sendmail
and calls sendmail.

I think that rmail can also process multiple messages in one invocation.
I don't think that directly translates to invoking sendmail.

rmail is an abstraction layer that is (indirectly) invoked as part of
uux reading the mail bag on it's standard input and then splitting it
out as necessary.

I'm fairly certain that rmail is called without any parameters and
assumes that everything is on STDIN. This means that systems sending
email via UUCP to the receiving system don't need to know anything about
the receiving system's email configuration.

> What program generates these strings?
> "From "
> "remote from"

The system sending the email.

I think that sendmail can generate them for outgoing messages.

> Why it's necessary to run rmail instead of directly running sendmail for uucp?

See above.



--
Grant. . . .
unix || die

[Claus Aßmann]

kevin shell wrote:

> What rmail does before execve(2) sendmail?

The man page claims:
Rmail interprets incoming mail received via uucp(1), collapsing
``From'' lines in the form generated by mail.local(8) into a single
line of the form ``return-path!sender'', and passing the processed mail
on to sendmail(8).

> What program generates these strings?
> "From "

sendmail can do it:
5.4. M -- Define Mailer
...
n Do not insert a UNIX-style "From" line on the
front of the message.

> "remote from"

U This mailer wants UUCP-style "From" lines with the
ugly "remote from <host>" on the end.


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