don't forget to write

Interjection

informal

(informal) Addressed to someone whose departure is permanent or for a long time

Japanese Meaning

（長期または永久の別れの際に）手紙（または連絡）を書いて連絡を続けるようにという別れの挨拶

Don't forget to write; you're leaving for good, and I'll miss you.

忘れずに手紙を書いてね。君は永住のために去ってしまうから寂しくなるよ。

Sense（1）

(informal) Addressed to someone whose departure is permanent or for a long time