Yes it is.
noreply@bitcointalk.org , is official bot email from Bitcointalk
You have been received this because your default notification setting was set to always. see pics links below
https://prnt.sc/kev8cuIf you don't want to longer received this set to "Never"
Regarding to your priv.message. Fourge send your message with quoting name of yahoo62278 which is one of trusted bounty manager here, so i think it is spam, just delete and ignored it. be careful with such a kind of message like this.