PopService is not creating issues with the default priority setting

I have the following Priorities defined in my configuration

Very High
High
Medium
Low

and in the Administrative pages, I have Medium defined as the default priority. When I create issues using the interface, it defaults to Medium as I would expect.

However, I have PopServices defined that create issues from emails, and everything is working with the PopServices except that the issues are being created with a "High" priority instead of the defaut

Here is my Service config:

Create Issue for MAUI-OPS
com.atlassian.jira.service.services.pop.PopService

handler: Create Or Comment Handler
popserver: [some-email]@uiowa.edu
handler.params: project=MXOPS, issuetype=4, catchemail=[some-email]@uiowa.edu
usessl: SSL (POP/S)
forwardEmail: [some-email]l@uiowa.edu