The main issue here is that your email server is most likely on a shared server.
Then along comes a new user on that same server and they start sending spam, then the IP for that server is blocked, and since you are on that server so is your email.
You need to contact email support each and every time you get notice of blockages so they can fix things.
NOTE: web hosting and email are normally on two different servers and can be hosed even by different providers.
Then along comes a new user on that same server and they start sending spam, then the IP for that server is blocked, and since you are on that server so is your email.
You need to contact email support each and every time you get notice of blockages so they can fix things.
NOTE: web hosting and email are normally on two different servers and can be hosed even by different providers.