I am/was also affected by this bug and can confirm that it is caused by leftover files from a former sendmail installation.
Because of this, I'll add the sendmail package to the bug.
Reinstalling sendmail removed the bug.
Doing an "apt-get purge" on all sendmail-related packages also removed the bug (and the offending files).
@ amichair Thank you for figuring this out! You probably saved me much time!
I am/was also affected by this bug and can confirm that it is caused by leftover files from a former sendmail installation.
Because of this, I'll add the sendmail package to the bug.
Reinstalling sendmail removed the bug.
Doing an "apt-get purge" on all sendmail-related packages also removed the bug (and the offending files).
@ amichair Thank you for figuring this out! You probably saved me much time!