Log level

The level of logging can be set for sendmail(1M). The default using a standard configuration table is level 9. The levels are as follows:

0

Minimal logging.

1

Serious system failures and potential security problems.

2

Lost communications (network problems) and protocol failures.

3

Other serious failures, malformed addresses, transient forward/include errors, connection timeouts.

4

Minor failures, out of date alias databases, connection rejections via check_ rulesets.

5

Message collection statistics.

6

Creation of error messages, VRFY and EXPN commands.

7

Delivery failures (host or user unknown, and so on).

8

Successful deliveries and alias database rebuilds.

9

Messages being deferred (due to a host being down, for example).

10

Database expansion (alias, forward, and userdb lookups).

12

Log all incoming and outgoing SMTP commands.

20

Logs attempts to run locked queue files. These are not errors, but can be useful to note if your queue appears to be clogged.

30

Lost locks (only if using lockf instead of flock).