Comment 1 for bug 1829292

Thanks for your report. I've been able to reproduce the issue and by digging a bit deeper I found two relevant bugs in Debian [1,2]. Also relevant is the changelog of the Debian exim4 package [3].

In my understanding this is what happened:

 * exim4 4.92 broke the compatibility with sa-exim [4].
 * exim4 4.92-5 (Debian package) dropped the patch to enable local_scan and has been
   declared incompatible ("Conflicts:") with sa-exim [3].
 * By including api-limitation.patch sa-exim 4.2.1-17 is made compatible with exim4 4.92.
 * exim4 4.92-7 is uploaded to Debian unstable with local_scan enabled again and the
   incompatibility with sa-exim removed.

The newer packages are already in Ubuntu Eoan (currently in development).
This bug can be fixed in Disco by porting those packages back.

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925982
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=926952
[3] https://metadata.ftp-master.debian.org/changelogs//main/e/exim4/exim4_4.92-7_changelog
[4] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=926952#19