From an Orthodox priest-friend:

A quote from the Patriarch HH Shenouda III, one of the heads of the Oriental Orthodox Churches and a former President of the WCC…

http://216.109.125.130/search/cache?p=protestant+ordinations+and+Orthodox+theology&prssweb=Search&ei=UTF-8&fr=FP-tab-web-t&x=wrt&u=tasbeha.org/content/hh_books/Comptheo/&w=protestant+ordinations+orthodox+theology&d=ZlkGHW1aMPxI&icp=1&.intl=us

The above reasons are our answers to the question, repeatedly asked of us: “why do the Orthodox Church re- baptise the converts from the Protestant denominations”? We could also say that we adorn them with all the spiritual treasures which they did not receive when accepted their Protestant baptism. We usually ask of them: “Have you received salvation in your baptism? Have you received righteousness, newness of life and the forgiveness of sins? Have you been clothed with Christ in baptism? Have you been born anew? Especially that you did not consider baptism to carry with it any of those graces

We also repeat the non-Orthodox baptism as a canonical priest did not conduct it, while our Protestant brethren refute human priesthood, as well as the teaching of the holy sacraments.

While it may have been administered in the Name of The Holy Trinity , we tend not to call the baptism of a Protestant convert “a re-baptism” as it lackes three important qualities:

(a) It was not administered by a clergyman

(b) It was not considered a Sacrament

(c) It was not considered to carry any spiritual efficacious

Endquote.

If a group denies the priesthood, then they obviously do not have it. No priesthood, no sacraments, said sacraments are the means of grace which belong to the Church.