Quick Quora thread on how clergy sign their names in the Anglican/Episcopal and Catholic church. They use the '+' as a sign and a way to send blessings to one another.

https://www.quora.com/What-does-the-plus-sign-+-at-the-start-of-a-signature-mean-For-example-if-someone-especially-a-Catholic-clergyman-signs-their-name-+-Michael

The general practice amongst Anglican/Episcopal and Roman Catholic priests and bishops is to sign their names with a cross as a way of sending a blessing. As far as I am aware, the practice began with Anglicans and Episcopalians and was adopted by Roman Catholic priests and bishops in the English-speaking world.

The convention is that a priest (or occasionally a deacon) signs it with the cross after his or her name (John+), while a bishop places it before his or her name (+John). I have occasionally seen deacons write their names with a slash, presumably to represent their stole, like John/.

Meanwhile, as David Aldred notes, on the Web a convention arose to always write bishops’ names like that as a kind of shorthand, using the Latin name for their diocese if there is one, such as +Southwark, and using two crosses for archbishops, such as ++Cantuar (Archbishop of Canterbury) or ++Ebor (for “Eboracum”, Latin for “York”).

If the clergyperson’s name is used instead of their diocesan or parochial title, then typically their first name is used, like ++Rowan or John+.

In e-mails within the The Episcopal Church (Episcopalians, aka Anglicans) talking about or with clergy, this can get a little out of hand, as some people insist on using the crosses and slashes for each and every clergyperson every time they are mentioned. (See Point of Personal Privilege: Of the "+" and the Names of the Clergy for an example.)