Strange Messages in procmail log

Hello,

I just found the following message several times in my procmail log:

> From jank(_at_)ifi(_dot_)uio(_dot_)no  Thu Jun 11 18:31:11 1998
 Subject: Fehler bei Kompilieren von I4L
  Folder: /home/hubert/Mail/Listen/isdn4linux.98.06                        3021
procmail: Couldn't determine implicit lockfile from "/usr/sbin/sendmail"
> From palme(_at_)uni-wuppertal(_dot_)de  Thu Jun 11 18:31:13 1998
 Subject: Excite indexing process finished.
  Folder: /var/spool/mail/hubert                                           1429

- What does this message (procmail: Couldn't determine...) mean?

- Which mail does it belong to?

Thanks in advance!

-- 
Hubert Palme
palme(_at_)uni-wuppertal(_dot_)de