ROM plays some tricks with message headers.

As specified by a RFC I simply can't remember the number, ROM will
set the In-Reply-To and References headers, which is a good thing for
e-mail software that have threading.

Besides from the, ROM will also do a dirt trick in the message delivered
with the -d parameter (the original message).
To make the user aware that the message was delivered through ROM (instead
of directly by the sender's MTA), it will set two extra headers, namely
X-Note and X-Delivery-Agent.

ROM will always set a X-Mailer header, naming itself as the mailer.

On top of it all, ROM sets all it's reply messages as Precedence: Bulk.
This is important, once ROM will not reply to List or Bulk messages.
This is done to avoid mail loops. In any case, the -d flag is still
honoured.

