Does the 'seen' come up at the end of a message if it's read through email?

[.]

If I haven't viewed the message through Facebook, but I've opened and read it through email notification, does the '✓seen' appear?

[Lucygoose20]

I'm not sure. I don't think so. But the easiest way to see if it has is to log into facebook, click your messages feed, but not on the message, and if the message is highlighted in blue, then they don't think you've seen it, if its white, the check is there.