Hi there, agrozier.

I appreciate you for sharing the information on how you resolved the issue about being unable to send an invoice by Comcast email. This resolution will surely help other users who encounter the same problem. 

You may want to visit these articles for your future reference:

• Set up email service.
• Error: Could not connect to the email server.

Please know that you're always welcome to post again if you have any other concerns with your QuickBooks. The Community team will always here to help. Wishing you and your business continued success.