PHP mail function stopped working after Plesk qmail reinstallation

One client's contact form that is using the PHP mail function suddenly stopped working. I thought it was a misconfiguration on sendmail:

[mail function]
; For Win32 only.
SMTP = localhost

; For Win32 only.
sendmail_from = me@localhost.com

; For Unix only. You may supply arguments as well (default: "sendmail -t -i").
sendmail_path = /usr/sbin/sendmail -t -i

You are using qmail!

Bummer! Looking back into my notes,I found out that qmail supports sendmail binaries so it doesn't matter whether PHP specifies the old path to sendmail.

And prior to that day, we reinstalled Qmail.(Server got hit by a spammer) So maybe we messed up a bit with the symlinks.

Solution:

Link the sendmail binary with qmail-sendmail using this command:

ln -s /var/qmail/bin/qmail-sendmail /usr/sbin/sendmail

That solved the problem. Hope this post helps you too.