Would love to know also as want MS SQL 2019 support but believe there are some Smartermail issues with the last release version?

Is the Beta with the Smartermail fix safe to use in production?

Our change log is currently available via github here: https://github.com/FuseCP/SolidCP/blob/master/CHANGELOG (altho 1.4.6 should probably be 1.4.5) some additional features and fixes are pending.

Due to the delay / work done on the new website and manuals it is currently a bit scares on new features (as most of our attention went elsewhere). to which we haven't made a new release just yet (we expect to do that end of Jan or Feb).

mssql 2019 is already supported in 1.4.4

Beta is called a beta for a reason, it is not thurrowly tested yet and might contain new/other issues we are not aware of.

In general it should be relatively stable to use, but unexpected behaviour is always possible with a beta.