Go to Admin / System Admin / System Defaults / Email Setup / SMTP tab
- Click on the Default line, and change the host name to smtp.mailgun.org for Mailgun, or smtp.sendgrid.net for Sendgrid.
- Usernames and passwords are the same for each different SMTP company, so no changes to the account info needs to be changed.
- Click Apply Changes
- repeat these steps for Track Notify, Invoice, and Agree Delivery
Apply Changes, and SAVE.