Postfix/Dovecot configuration

Probably your mail server is an open relay or a source of backscatter mail so it appears in many blacklists. The procedure to fix your server includes detecting how it is misconfigured, correct any configuration error and contact the various blacklists operator and ask for delisting. For $200 I can fix your mail server configuration plus I can enhance it, configuring TLS (encrypted mail), DKIM, SPF and DMARC to improve your outgoing mail deliverability. I can work over teamviewer or preferably via shell access to the server. In a day your server should be cleaned up and after 24-48 hours you will begin to get delisted from blacklists.