E-mail stealing and domain sabotagging by email spammers

[konstanta]

Some email marketing company that sends tons of junk mail is using my email as the from address and also my clients domains for spamming as from address. This behaviour has caused that me email address is rejected from most servers or spam filter and my clients domain has almost disappeared from the search engine although has been for more than 3 years listed with good ranking and listing in the first 5 positions for its keywords by just applying the search engine guidelines. How can I clean my email address and my clients domain and get it listed again in the search engines?