Sendmail Operation Guide

Debugging

There are a fairly large number of debug flags built into sendmail(1M). Each debug flag has a number and a level, where higher levels means to print out more information. The convention is that levels greater than nine are absurd, for example, they print out so much information that you wouldn't normally want to see them except for debugging that particular piece of code. Debug flags are set using the -d option; the syntax is:

debug-flag:: -d debug-list
debug-list:: debug-option [ , debug-option ]
debug-option:: debug-range [ . debug-level ]
debug-range:: integer | integer - integer
debug-level:: integer

Spaces are for reading ease only. For example,

-d12: Set flag 12 to level 1.
-d12.3: Set flag 12 to level 3.
-d3-17: Set flags 3 through 17 to level 1.
-d3-17.4: Set flags 3 through 17 to level 4.

For a complete list of the available debug flags you will have to look at the code (they are too dynamic to keep this documentation up to date).