keep me posted.

（何かあったらまた連絡ちょうだい。）
　e-mailの英語。単純だけど知らなかった言い回し。"keep someone posted" で「絶えず最新情報がわかりようにしておく（to regularly tell someone the most recent news about something）」こと。

• • Keep me posted on anything that happens while I'm away.
  • I'll keep you posted on his progress.