noun
address change; redirection
Computing term for changing the destination address, such as for email or package forwarding.
メールのあて先変更を設定する。
Set up email redirection.
引っ越しの際に郵便物の宛先変更を申請した。
I applied for mail forwarding when I moved.
転送 means 'forwarding' or 'transferring' something already received, while 宛先変更 specifically refers to changing the destination address itself.
Compound of 宛先 (あてさき, 'address') and 変更 (へんこう, 'change').