Need to set mailx variable to specify the From address

Question

Running Oracle Linux 5.8 (which is just re-branded RedHat EL 5.8) I must change the From address. But we have scripts that use mailx which cannot be re-written to use any extra flags, so I'd like to use internal variables instead, which I see on the linux.die.net manpage on mailx is an alternative to the -r flag:

-r address
Sets the From address. Overrides any from variable specified in environment or startup files. Tilde escapes are disabled. The -r address options are passed to the mail transfer agent unless SMTP is used. This option exists for compatibility only; it is recommended to set the from variable directly instead.

(Source: http://linux.die.net/man/1/mailx)

How can we use these mailx variables? I tried adding this to /root/.mailrc, no go:

set from=[e-mail]

I also added that to /etc/mail.rc with no gold. So I am turning to you, SuperUsers...

Answer 1

Neither using -r nor setting the from variable worked in my environment.

I always got something like:

send-mail: 550 5.7.1 ... Invalid from address ....

What worked for me was adding an sSMTP alias to /etc/ssmtp/revaliases, e.g.

accountname:[e-mail]:smtp.example.com

Answer 2

I'm sure versions matter, but I just struggled with this very problem on RH Server 6.7, having misread the mailx manpage, but eventually I got ~/.mailrc to work.

set from=[e-mail]
set replyto=[e-mail]

doing both from and replyto is probably unnecessary, but if it's worth doing, it's worth overdoing!

Answer 3

I just tested this in Ubuntu 14.04 and using the -S parameter worked for me:

-S variable[=value]
          Sets the internal option variable and, in case of a string option, assigns value to it.

So, the following command sets the from address to "[e-mail]":

echo "This is my test" | mail -S from="[e-mail]" -s "This is my subject" "[e-mail]"

Answer 4

To add to Richard Betel's answer, you can also specify a full email address in .mailrc, like:

set from="John Smith <[e-mail]>"

Answer 5

Apparently it's not possible to set a mailx variable to do this. This is done with a Sendmail (or equivalent MTA) configuration. But unfortunately no Sendmail configuration was workable for us, and we have to use the -r flag.