[php] Undelivered Mail Returned to Sender Opcje

[Zmorcia]

Witam, mam skrypt hostingu e-maili, i napotkałem taki e-mail gdy chce wysłac wiadomość do tego skryptu np cos@mojedomena.pl toodrazu dostaje odpowiedz na e-mail:

This is the Postfix program at host mailout1.go2.pl.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The Postfix program

<postmaster@callshot.eu>: host callshot.eu[66.7.215.213] said: 550 No Such
User

A wiadomość do hostingu niedochodzi jaki to problem ?
Here (in reply to RCPT TO command)