I’m surprised nobody here mentioned SoGO. It’s a fully featured web mail interface that integrates contact management and a web calendar including caldav, carddav and task support. Easy up setup and easy to connect to any phone via foss apps.
This is your browser handling the content disposition wrongly.
I use SoGo for that.
Cal and task sync. Card dav, Email und calendar in one neat web interface
Indeed.
Its open source, not free software.
Tests, Documentation, License, Maintainance and clear inheritance processes.
Modular solution. Big NAS for backup and file and media serving shuts down when I go to bed automatically or nobody is home. Boots via WOL when needed.
Always on services on a central pi for home automation, phone and internet services, etc.