[Zope] pipedream : fork a dtml-method within zope ?

[chas]

Consider a discussion forum product where a dozen people
have already participated in a particular thread.  These
people, when posting their messages, checked a box which 
said "email me when somebody else responds/adds to this 
thread".  (Yes, this is nicked from Cold Fusion Forums :-)

Now, a 13th person adds his 2 cents to the thread and posts
a response. We want to now send a mail to each of the first
12 participants. 

No problem so far, except mailing all 12 people is going to
take quite a bit of time, and contributor #13 is going to 
get impatient waiting whilst this is happening. Then imagine
a discussion thread with dozens of participants/posts. 

Solutions :

a. Write some script to go through the discussion 
   forums looking for such follow ups and mail the 
   previous participants in the discussion thread. 
   Cronjob it. Tiresome/boring and not as 
   instantaneous as I'd like. 

b. Is it possible in any way to fork that mailing 
   process (which is actually just one dtml method), 
   so that it can be completed without slowing down 
   the rendering of the page ?
   I'm guessing this is totally beyond zope.

Or am I overlooking something obvious ?

TIA,

Chas