I run my own small-company mail server with 10 high-use accounts (using Zimbra, but it's mostly dead, so looking for alternatives). We lease small /29 blocks f

I run my own small-company mail server with 10 high-use accounts (using Zimbra, but it's mostly dead, so looking for alternatives). We lease small /29 blocks from OVH for our various services. Haven't had many issues in the past 5 years, except once when a user was hacked and spam was sent. 48h later things were back to normal.