Its interesting that OX are on the list, because OX appear to be going down the road of freezing open-source featureset and reserving (new) advanced features for their commercial customers.
The Dovecot commercial product manager has for example said in a presentation[1]:
"there will be an open source version, but that open source version will be maintained for single server use only. we are actually taking out anything any actually kinda' involves multiple servers, dsync replication and err some other stuff. so dovecot will be a fully-featured single node server"
The Dovecot commercial product manager has for example said in a presentation[1]:
"there will be an open source version, but that open source version will be maintained for single server use only. we are actually taking out anything any actually kinda' involves multiple servers, dsync replication and err some other stuff. so dovecot will be a fully-featured single node server"
[1] https://youtu.be/s-JYrjCKshA?feature=shared&t=912