UNIX for Beginners Questions & Answers

echo "Message Body Here" | mail -s "Subject Here" someuser@gmail.com

       
        --debug-level=LEVEL
	      set Mailutils debugging level

       --[no-]debug-line-info show source info with debugging messages

https://mailutils.org/manual/html_node/Logging-and-Debugging.html

3.9.1.3 Logging and debugging
The default behavior of sieve is to remain silent about anything except errors. However, it is sometimes necessary to see which actions are executed and on which messages. This is particularly useful when debugging the sieve scripts. The --verbose (-v) option outputs log of every action executed.

Option --debug allows to produce even more detailed debugging information. This option takes an argument specifying the debugging level to be enabled. The argument can consist of the following letters:

‘t'
This flag enables sieve tracing. It means that every test will be logged when executed.

‘T'
This flag enables debugging of underlying mailutils library.

‘P'
Trace network protocols: produces log of network transactions executed while running the script.

‘g'
Enable main parser traces. This is useful for debugging the sieve grammar.

‘i'
Trace the program instructions. It is the most extensive debugging level. It produces the full execution log of a sieve program, showing each instruction and states of the sieve machine. It is only useful for debugging the code generator.

Note, that there should be no whitespace between the short variant of the option (-d), and its argument. Similarly, when using long option (--debug), its argument must be preceded by equal sign.