It's just as much a part of the message as ... the message.
Only in that it's attached to the message, just like tag lines are. They hav no connection to the message body.
If you are not the sysop, I agree. If you are the sysop, which was the
case in this discussion, you have full control over that and are aware
what is being sent every time you enter a message.
As most modern BBS softwares allow you to enter a custom origin line for
each network (and sometimes each area), it would be very smart not to
include political messages in lines meant for any networks that don't
allow politics, especially if said discussions bother you.
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