Decode =?ISO-8859-1? subject lines?

[Geoff]

Hello all,

After a few months of operation and some tuning to allow for
the random words issue, bogofilter is now working extremely
well on my system.  Most days not a single item of spam gets
through and I have seen only one false positive.

Procmail applies bogofilter and sends the spam to an
ordinary directory.  I periodically run as simple shell
script to grep the subject fields to check to false
positves. A significant proportion of the spam has an
encoded subject line commencing=?ISO-8859-1?. I assume that
this almost inevitably means that the mail is spam and can
be safely discarded, but I would like to be able to read it
just in case.  I have googled a good deal, but have not been
able to find script or utility which will decode such lines
and which I could incorporate into my shell script.  Can
anyone point me to one please?

Thanks.

Geoff