E-mail notification subjects are localized with actor locale, not recepient of the message. Thus I do receive messages in 4 lanugages: english, russian, french and german while my own locale is set to english.

Samples (subjects of the E-mail messages I receive from jira@jetbrains.net):
[JETBRAINS-JIRA] Erstellt: (IDEA-662) PeerFactory.getStructureVeiwFactory typo error
[JETBRAINS-JIRA] Assigned: (IDEA-662) PeerFactory.getStructureVeiwFactory typo error

[JETBRAINS-JIRA] Creee: (IDEA-621) Propagate parameters: make it work with "Introduce Parameter"
[JETBRAINS-JIRA] Assigned: (IDEA-621) Propagate parameters: make it work with "Introduce Parameter"

[JETBRAINS-JIRA] Создан: (IDEA-568) Support for Long CamelHumps
[JETBRAINS-JIRA] Kommentiert: (IDEA-528) Infinite loop and subsequent OOME on "Complete Line" action

while not actually very important still makes configuring rules in mail client a painful task. I do receive a lot of notifications and I'd like to separate comments user may add from workflow change notifications that usually not important for me.