Convert MSMESSAGESTORE to EDB

Although both .msmessagestore and .edb files are based on Extensible Storage Engine (ESE) database format, it is unlikely one can be just simply converted to another and vice versa. At best you can find and use some  ESE format viewer, explore the databases for some kind of export and save that, but a conversion between .msmessagestore and .edb files seems to be unlikely. No dedicated converter for direct msmessagestore to edb conversion exists.

Simply put, it is impossible to convert MSMESSAGESTORE to EDB directly.
Thus, there is no so-called msmessagestore to edb converter or a free online .msmessagestore to .edb converter to be found.