This username seems targeted by spambots.
This is an account intended for automated tools, and so we should avoid to have too much noise when debugging why a tool doesn't connect.
Oct 19 19:44:09 ysul sshd[23342]: Invalid user deploy from 202.117.35.252
Oct 19 19:44:09 ysul sshd[23342]: input_userauth_request: invalid user deploy [preauth]
Oct 19 19:44:10 ysul sshd[23342]: Connection closed by 202.117.35.252 port 32264 [preauth]
Could be the account used by Jenkins to deploy static sites, if not alken orin.
Should be documented.