I can receive email with Comcast but cannot send it

Ok, then your settings are most likely correct and you will just need to update the password in the SMTP settings. There is usually a password field for incoming mail which is POP3/IMAP and one for the outgoing mail which is the SMTP server. The password is the same in both spots and you will need to enter the new password there.

Settings > Mail > Accounts, and choose your mail account.

My Comcast mail is a POP3, so the screen I have may be a little different if you are using IMAP. Hopefully with the information I provided, you will be able to navigate to the correct spot to change the password. If you get stuck, let me know what you are seeing on the page.

FYI, to take a screenshot:

Take a screenshot on your iPhone - Apple Support

and to post the screenshot you would choose the Image Insertion option when postings. You would still want to make sure your email is redacted before posting.

No Screenshots appeared on your post. As stated if you account is an IMAP account, your screen will look different. On the POP3 account, you would tap SMTP where the star is in the first screen shot and then after selecting the server, the last screenshot shows where you would put your new Comcast password.

That sound like a problem with the SMTP settings. Go to Settings > Mail > Accounts, and tap on the account giving you trouble. Scroll down on that page and check the setting under SMTP. It should show "smtp.comcast.net". If that one is showing there, you can tap on it and check the settings. Start by entering your password on that page, this is the password you would use to login their website at www.xfinity.com. Also the Use SSL setting should be checked, the Authentication should show "Password" and the Server Port is 587.

Was this account recently set up or did you just start having the issue?

Is the account using POP3 or IMAP?

The settings are usually different depending on if you are using POP3 or IMAP. POP3 is when you can delete an email on one device and it is not affected on another device using the same email. When using IMAP, deleting on one device will also remove it on any other device that uses the email. It does show on the settings screen after you tap the Account whether it is being set up as POP3 or IMAP.

It may help if you can provide screenshots of that settings page as well as the SMTP settings page, just make sure you block out your email address.

The password in the screenshot is for your incoming mail, you will need to tap the SMTP selection, then the server again to get to the password for sending emails. Type the same password there. The page will look like the second screenshot I provided with "smtp.comcast.net" on the top of the page.

This is a user to user forum, no one here is going to receive email from you. Post the screenshot in this forum.

We cannot receive emails.

On the second screenshot is where you will have to enter your new Comcast password.