What's with the black dot?

[Tilt]

Can someone tell me what the black dot is in the envelope icon to the left of each post? Does it have something to do with the number of posts you have posted or something? I have searched the site for a clue but to no success.

[WarHULK]

It means that it's a thread you've left a message in.

[shin-goji]

The black dot was a founding member of the JLA...

[WarHULK]

That's right! I'm sorry I forgot that, I have to admit my DC knowlage is a little rusty ;)

[Tilt]

Thanks guys. For both the info and the laughs.