is there just one database file somewhere - knowledge-base seems to suggest there is? Or is there one database file for each email account
By default “all eM Client mail data are all located in the following hidden database folder”, unless you have changed it via “Menu / Settings (Preferences) / General / Storage”
Windows default location is C:\Users%username%\AppData\Roaming\eM Client
Mac default location is /Users/yourusername/Library/Application Support/eM Client
I have two in use - one IMAP / web; one POP / local. To move my email app to another machine the Help says I can copy the database file - if I can find it!
To transfer “the exact mail database including local folders and all complete settings etc to a new computer”, you would “either use the built-in Backup and Restore” or “copy the complete eM Client hidden database folder contents” as per the eM Client blog link instructions below.