[Help-mcron] How to use with-mail-out in mcron guile file?

[guix]

Hello,

I have asked Mathieu, but it is better to ask on the mailing
list.

I would like to use the with-mail-out with mcron.

> (with-mail-out (job "something" "do") address@hidden)

The info file for mcron says:

3.1.2 Sending output as e-mail
...
...
configuration files.  The command (with-mail-out action .  user) can be
used to direct output from the action (which may be a procedure, list,
or string) into an e-mail to the user.

I would need real world example, as I have just replaced
local user's mcron, it works well. Only that I need emails
sent.

Jean Louis