KanjiJLPT N4
Send

escort, send

Mnemonic

You need to send an urgent letter, so you strap it to a deer's antlers and slap its rump. The deer rockets down the forest path, hooves thundering, delivering your message faster than any mailman ever could.
Additional thoughts
Picture the deer sprinting down a narrow dirt path with a glowing envelope lashed between its antlers — the image of nature's express courier makes 'send' unforgettable.
Quick recall
Send a letter by strapping it to a deer and launching it down the path.

Details

The keyword for 送 is send. This kanji refers to the act of sending, transmitting, or dispatching something or someone from one place to another. It also carries the meaning of escorting or seeing someone off, as when accompanying a departing person on their way. More broadly, it can refer to spending or passing time, as in living out one's days.
On'yomi
そう
Kun'yomi
おく.る