Will it say "seen" on a Facebook chat when you check message notifications from your email?

[TREASURE]

When it notifies you by email that "[name here] has sent you a message", if you open that message will it say on Facebook that the message has been "Seen"?
When it notifies you by email that "[name here] has sent you a message", if you open that *EMAIL will it say on Facebook that the message has been "Seen"?

[Danny]

No

[?]

nope

[Andrew]

Not by opening the email (via Yahoo! for example), but by opening the message (via Messenger or Facebook) yes; furthermore, there is a way to choose people who cannot send you messages. Instructions to do this will be in the edit section of this response.

Edit: the only way to block communication is to block the user as well. If you still want to be Fb friends without them knowing that you have read the message, simply delete the message without opening it.