If you cannot send emails in Comcast, then there might be a problem with your internet connection or an issue with your browser. You can use the step given below to troubleshoot the issue so that you can continue sending emails from your Comcast account:
• No mistake while typing the email address.
• Ensure JavaScript is enabled on your browser
• Sign out of Comcast and then sign in again.
• Make sure the recipient has not blocked your email address.
• If you send an attachment along with the email, make sure it does not exceed the size limit.
If you need to implement a more advanced solution to fix the issue, you can call the Comcast email customer service and ask for additional technical assistance.
Read more for: https://www.contact-emails.com/comcast/