token pairs [was: Algorithm limitations]

[Boris 'pi' Piwinger]

Tom Anderson wrote:

>> There is the risk that this creates a token pair which looks
>> like a tagged entry, since both use a colon.
> 
> That would be very dangerous... we can't give spammers the ability to
> craft email bodies which get mistaken for or screw up the header
> classifications.  Perhaps another character should be used, such as the
> period.

Period is allowed in the standard lexer. How about =?

pi