Discussed on roundup-users a while ago -- I 
suggested that in installations like ours which run 
multiple trackers it'd be useful to include the 
tracker name in the Subject line of email sent by 
Roundup.

Richard commented:

--
I won't be able to reliably remove the subject line 
syntax (see below) but I _could_ make it more 
flexible to allow:

  [issue123]
  [Roundup tracker name issue123]

as alternatives achieving the same goal. 
Configuring the email subject line is another issue -
 I'd say that a simple on/off switch enabling the 
tracker name in the subject line as above would be 
sufficient. That means it's just a config variable, 
and that's quite easy to implement and use.
--

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While we're at configuring the subject prefix, a user has requested that the 
square brackets [] be optionally changed to braces {} (or, potentially, <> or () 
as other options). These are all ideas that might be nice to try for in 0.6. 
 
As always, volunteer submissions of code are welcome :) 
 

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FWIW, the original roundup-users thread starts here:

http://sourceforge.net/mailarchive/message.php?
msg_id=2240915

Can not open links in msg3111.
It looks like the discussion is here:
Prepending tracker name to emails from roundup -
http://roundup-users.narkive.com/yOurppNR/prepending-tracker-name-to-emails-from-roundup
I also need this feature, thanks.