1) Segment addresses for business communications and make a second list for general use
Also, create a disposable address in which you place anything that’s not important to you or that you want to specifically keep separate.
2) Make sure that you mark unwanted mail as spam
Hotmail and Gmail will create a filter to automatically spot all future mail from that source as junk and it will submit a complaint against the network that sent the mail to reputation monitoring services. Make sure that you do your part and select it as spam, so mail services company can do the rest.
3) It is very important to Unsubscribe
A high-quality email marketing company will ensure that their users include unsubscribe options in all email headers and / or footers as well.