@WalterH I also had this issue yesterday morning after updating to:
2024-04-29T06:03:16+0200 DEBUG Upgraded: grommunio-sync-2.0.90.62b136b-157.2.noarch
2024-04-29T06:03:16+0200 DEBUG Upgraded: grommunio-web-3.8.1.g551bee16-66.1.noarch
2024-04-29T06:03:16+0200 DEBUG Upgraded: gromox-2.27.84.g3c69d18-27.1.x86_64
2024-04-29T06:03:16+0200 DEBUG Upgraded: mapi-header-php-1.3.15.9888b00-6.1.noarch
I had no gromox.cfg in place, also outgoing_smtp_url was unset. Maybe the devs could check the hardcoded defaults of the delivery service. To me, it seems as if there is an invalid default value (maybe empty).
@MichaelH thanks for sharing!
bye
Daniel