Email Security: Can someone use my domain-based email ID without my authorization?

Hi folks,

I'm not a php programmer at all, so I don't even know where 'square one' is when it comes to that stuff.

I also hope that I'm posting this under the right category.

However, I just received an email out of the blue - of course, from a smart marketer (php developer working with email security), who's obviously trying to get me a bit freaked out, so that he can pitch me his services.

Here is what he says:

I am writing to ask whether you are aware that your domain configuration has serious security issues which lets anyone use your email address without your authorization?

This means anyone can use your email address and send emails to anyone of their choice, let it be your business colleagues, friends or anybody for that matter. I do not have to explain the consequences here since it is obvious; It will breach your privacy and could cost you in professional dealings. Just to prove this to you, I can send an email to you from "your email address itself".

Do you want me to send an email to you from your mailbox itself, so you can see the problem?


He's probably right, but I'm not interested in responding to him because he's just trying to pitch me his services.

However, what do you guys recommend I do under the circumstances - seeing that he's probably right?

I'd appreciate any good advice - something that I can do on my own - easy enough.

Thanks in advance.