How to fight spam using our domain name?

Spammers doing a spam campaign by email using our domain name

[supermanu]

Dear all,

We are victim of spammers doing a spam campaign by email
These spammers are using our domain name as base of their FROM email address

i.e. FROM: [e-mail]

In their message, they ask to not reply to the FROM email but use instead an alternate email address inside the message body

People receiving the spammers message put it on spam and as a result, it affect greatly our website.

I would like to know if you have a method to fight against this kind of spams

Thank you in advance.

[brotherhood of LAN]

supermanu,

It's not all that uncommon, you might find some of these threads [google.com] of interest