In the PHP mail function there is an "-f" parameter that is "return path", is this the address that a bounce back is sent to?
Let's see if I can ask this without making it sound complicated...
I have two servers, one is main-domain and one is email-helper, the email-helper domain sends email for main-domain, if I send from email-helper domain and forge sender as noreply@main-domain then any bounce backs will go to main domain and filling the email queue on mail server that didn't actually send anything, correct?
Will receiver servers have a problem if I send from email-helper with forged "from" noreply@main-domain and return path to noreply@email-helper will this be correct?
(And that probably means I have to set spf records on main-domain to designate mail-helper as allowed sender).
Thank for any help.