Hi,
I can help you. Gaining reputation of mail server is an easy job for who know what to do. With this I can help you do this:
1/ Refine setting of your email server (SMTP server) to conform with standards (virus scanning, spam filters, dkim signing, SPF etc.) as well as domain settings to ensure persistent sending/ receiving.
2/ Contact with Spam blacklists to clear your server IP(s).
Remember that every attempt to clean mail server reputation requires time and patience (white-listing is much more difficult than blacklisting).
Hire me if you interested.