The Comments: header is used to place explanatory text into the header portion of an email. The field portion of the Comments: header can contain arbitrary text.

One possible use for a Comments: header would be to notify recipients that one person is replying to mail for another:

Comments: Ben is in France for the next month or
          so gathering information for the meeting.
          I am handling his mail while he is away.
    
   whitespace

The Comments: header should rarely be declared in the configuration file. If it is, it should be prefixed with appropriate ?flags?. For example:

H?B?Comments: Local delivery is experimentally being handled
       by a new program. Complaints to root.

This comment is included only in headers that are delivered via the local delivery agent because that delivery agent is the only one to include the F=B flag:

Mlocal, P=/bin/mail, F=rlsDFMmnPB, S=10, R=20, A=mail -d $u

This declaration causes the new Comment: header to be added to the mail message.