Testing for user never posted?

[JamesAB]

I'm working on a mod in attachment.php

I know $vbulletin->userinfo['posts'] could be '0' (zero) even if a user has posted before but their posts were deleted or are in a forum that doesn't count posts.

What's the best way to test if a user has never posted before?

Would testing $vbulletin->userinfo['lastpost'] work? If they have never posted before would this value be NULL or '0' (zero)?

Or is there a better way to definitively test if a user has never even tried to make a single post in the past?

Thanks for your help,
James