Option 1:
Create an Email Log tab on Purchase Orders that shows log of Emails tasks of Purchase Order.
Log should contain Date, Time, User, Email To, Subject, Body. It should also allow you to view the Purchase Order Report sent, and the ability to "Resend" that will create a new log entry with Email To, Subject, Body and Report being identical to the original.

Option 2 (Preferred):
Enhance the Email option so that it actually launches a Communication screen linked to the Service Request and Purchase Order (linking Comms to PO isn't currently an option so this would need to be added as myPurchaseOrder, PO would then need to also show list of linked Comms).
The Communication would default to the Outsourced To record on the Service Request. Users can then click the "Email button" where they can select an Email Template if desired (allowing for more business appropriate/standard emails being sent). After progressing through the Email Template stage, the user is then presented with Greentree's standard Email screen which behaves as normal, with the exception being that the Purchase Order report is already listed as an attachment.

Future Enhancement Options:
The Email Template Maintenance (CRM > System > Utilities > Email Template Maintenance) option could be further enhanced to specify a list of Attachments where they are saved on a network file path (they can specify the display name and the file path to the file). That way a user could setup an email template to automatically attach certain files relevant to that template (e.g. Terms and Conditions).