Check to see if a user has posted in a certain forum

[wirewolf]

I've looked around and can't find any info on this. Running vbV3.0.5
I have custom messages for different groups and users at the top of my header (script is in phpinclude_start, with some conditionals to check for the groupid) and bbuserinfo conditionals (checks for bbuserinfo[postfields]) in my message templates. One thing I would like to add is a conditional in the message templates to check if a user has posted in my "Intro" forum.
Basically:
<if=condition=yes bbuserinfo[id] they have posted in forumX>
message1 </if>
<if=condition=no bbuserinfo[id] they have not posted in forumX>
message2 </if>
Just not sure of the syntax, or if the forumid can be pulled here in phpinclude_start, or is there some form of bbuserid that can be used with forumid in the template directly.
Any hints?
John