Currently if someone wants to use mail merge from LO, she has to enter e-mail credentials in the Options - LibreOffice Writer - Mail Merge E-mail settings panel.

This is problematic in enterprise environments with many users, few administrators and a password policy that makes passwords expire after some months.

A better solution would be to - optionally - integrate the acquition of such data (Name, E-mail, Outgoing mail server user name and password) with the OS level user credential handling.

On Linux, I think this should be possible using gnome-online-accounts, for example.
On Windows, I'm told there are excellent SSO APIs for this as well.