Currently, this issue is a known bug with the software and is slated to be resolved with the release of IGAM 6.5. The short-term solution is to use default Requirement Submission emails from the form to send to your users.

To restore these defaults, please take the following steps: 
1) First open the affected form in the IGAM Form Design Wizard
2) Within the form, go to Links tab
3) In the Links tab, open the Requirement Submission email under Automated Emails
4) Click "Reset to Default", then "Save and Close" to save your changes

You may also make custom changes to the Default email, if you wish to add customization, by doing the following:
1) Go to Tools, then choose Preferences in IGAM
2) Highlight the Applicant/Grantee View > Options at the bottom
3) Once highlighted, click Edit
4) This brings you to the Site [0] - Default window; please click the Emails tab
5) Under the Email Contents, there is a dropdown for E-mail Type; select Requirement Submission Confirmation and make changes to this message as you wish