Custom field default values aren't applied issues created by email

When an issue is submitted by email to the Service Desk mail handler, the default value is not applied to the issue for select lists.

Steps to reproduce:

1. Create a custom field called "contact type" that is a select list
2. Add values of "helpdesk", "email", and "other"
3. Set default value to be "email"
4. Submit request by email
5. View issue and note that custom field value is not the default of "email"

Expected results:
The value for "contact type" is email.

Actual results
It seems to pick the last value entered in the list of options.