We have been using SMX for a while at work now and as each year goes by I am less and less happy with their service and their lack of functionality
I did look at proofpoint on the recommendation of our firewall vendor and really liked the product but it was literally 10x the price that we currently pay to SMX and while I could see the value others didn't
After some real world recommendations of something that has good support spf, dkim and dmarc.. the ability to recall mail from users mailboxes, easy to manage rules and good av filtering, the ability to sandbox would be a bonus but not a requirement at this stage
I think i'll have a better case to work with to spend a bit more money now having more people working from home but we are limited with funds and would be interested in geekzoner recommended alternatives
Our mailserver is on prem and while a hosted mail filtering solution is preferred im not opposed to an on prem solution either
edit: didn't want to name and shame.