You don't need a letter. Just fill out an application .

A solicited application letter is sent in response to a specific job opening or request for applications. An unsolicited application letter is sent to a company without any particular job opportunity being advertised, to express interest in working for them in the future.

An unsolicited attachment is responding to an email with a resume as an attachment. If you do not follow the employers policy, they will not be likely to even open your application.

It is "Solicited" and "Unsolicited"

Unsolicited mail comes from like advertisers trying to get you to buy something while solicited m,ail comes from your friends.