This is the 10116th most frequent Japanese word.
郵
"郵" means "mail" or "post" in English.
Here, '郵' is part of '郵便局', meaning 'post office', where '郵' pertains to mail or postal services.
これは郵便局です。
This is a post office.
In this sentence, '郵送' refers to the act of sending something via postal service, using '郵' in the context of mailing or sending.
郵送で書類を送りました。
I sent the documents by mail.
The term '郵便配達員' incorporates '郵' to signify a profession related to mail delivery services.