Yes, if I log into the interface using the service account I see the edit button. What permissions need to be added to security role for that to show.
Current role has:
Allow Read Storage Quotas (Exchange) User
Allow Write Mailbox Rights (Exchange) User
Allow Write Storage Quotas (Exchange) User
Allow Read Automatic Replies (Exchange) User
Allow Write Automatic Replies (Exchange) User
Allow Read 'Hidden from address lists' Property User
Allow Write 'Hidden from address lists' Property User
Allow Create Contact Objects All object types
Allow Delete Contact Objects All object types
Allow Write Send As (Exchange) User
Allow Write Send on Behalf (Exchange) User
Allow Read 'Members' Property Group
Allow Write 'Members' Property Group
Allow Read All Properties User
Allow Write Calendar Permissions (Exchange) User
Allow Create User Objects All object types
Allow Write 'Account expires' Property User
Allow Move Objects From Container Computer
Allow Move Computer Objects To Container Organizational unit
Allow Write 'Display name' Property Group
Allow Write 'Group name' Property Group
Allow Move Computer Objects To Container Container
Allow Create Group Objects All object types
Allow Write 'Account options' Property User
Allow Delete Group Objects All object types
Allow Write All Properties Contact
Allow Modify Owner Group
Allow Read All Properties Document
Allow Write 'Password last set' Property User
Allow Write 'Lockout-Time' Property User
Allow Write 'User cannot change password' Property User
Allow Write 'Password self-service unblock date' Property User
Allow Reset Password User
Allow Write 'Name' Property Group
Allow Write 'Group name (pre-Windows 2000)' Property Group
Allow Write 'ms-Exch-Delegate-List-Link' Property User
Allow Read All object types