[SpamCop-List] Spam Subject Lines Ending With Number

[Chris W]

G'day,

I've noticed of late that much of the Spam I receive (up to 10 a day) has
the usual rubbish in the subject field but appends a number.   The number is
usually separated from the subject text by a large number of spaces,
presumably so it isn't always seen in the mail reader's display (truncated).
Is there some nefarious purpose to this number?

I thought that it may be used by the spammer to identify the complaining
spammee even if their email address is removed from the SC or other report.

Chris W