Another weird mailing issue

[eluser]Y0shi[/eluser]
Hi all,

when we were moving our host shortly, I found an issue that when I send an email, the sender always becomes something like: 7724. But this number or what ever isn't typed in anywhere?!

Here you got an excerpt of my print_debugger:

Code:

User-Agent: CodeIgniter
Date: Fri, 2 Sep 2011 12:44:05 +0200
From: "Info"
Return-Path:
Reply-To: "[email protected]"
X-Sender: [email protected]
X-Mailer: CodeIgniter
X-Priority: 3 (Normal)
Message-ID: <[email protected]>
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="B_ALT_4e60b37558daa"

And here you got the header piece of my email program:

Code:

Sender: 7724 <[email protected]>

It's weird, isn't it?

Can you imagine some server setting doing this? Please help.

BTW: We're mailing standardly with mail().

Regards.