Translation guide
The act of sending something on to another destination, such as mail, messages, or calls. In Japanese, the expression depends on what is being forwarded and the method.
forwarding (mail/email/calls)
To have mail or packages sent to a new address
General term for forwarding physical mail or packages. Often used with する.
Can you forward my mail to my new address?
Mail forwarding service, often used when moving.
I applied for a mail forwarding service when I moved.
To send a received email or message to another person
To redirect an incoming call to another number
To send goods onward to a final destination, often via an intermediary
To forward an email while keeping the original as an attachment
Specifically means to forward as an attachment.
I will forward the original email as an attachment.
転送 (tensō) is the general term for forwarding messages, mail, or calls. 回送 (kaisō) is more specific to sending things on a circuit or forwarding vehicles/goods, and is less common for digital communication.