I am having trouble receiving new mail

What type of email account - POP, IMAP, or Exchange?

If not a MobileMe account, not a Yahoo account that was created with the Yahoo account preset on the iPhone, or not an Exchange account being accessed via ActiveSync with the Exchange server, you are not accessing the account via Push.

Make sure you are set up like this http://www.ehow.com/how2175790check-comcast-email-iphone.html

Mind you, its Comcast so anything is possible 🙂

Then messages are not being pushed to the iPhone. With a POP account, the account can be automatically and/or manually checked for new messages at the incoming mail server for the account, which are Fetch settings.

Since you are also accessing the account with an email client on your computer, what is your account setting for removing messages from the server when downloaded with the email client used on your computer for accessing the account?

Do you leave the email client used on your computer for accessing the account launched and running actively checking the incoming mail server for new messages while your iPhone is doing the same? If so, there lies your problem.

Although it is possible to access a POP account with more than one email client, a POP account is designed to be accessed with a single email client only.

None of this is a problem with an IMAP account, which is specifically designed to be accessed with more than one email client at a time with the ability for more than one email client to access the account's Inbox mailbox and any other server stored mailbox for the account at the same time.

Are you accessing the account with an email client on your computer such as with Outlook or Outlook Express with Windoze?

If so, there is a setting for the account with the email client used on your computer for accessing the account for removing messages from the server when downloaded.

If you have selected to remove messages from the server when downloaded with the email client used on your computer for accessing the account and you leave the email client on your computer launched and running actively checking the account for new messages when you are not using the computer, any new messages received by the email client used on your computer for accessing the account are being removed from the server which makes the messages no longer available on the server for the iPhone's Mail application to download.

If you use an email client on your computer for accessing the account, do you leave the email client on your computer launched and running actively accessing the account for new messages when you are not using your computer and while your iPhone is doing the same?

No comcast is my home page...right thru to comcast.

So this means you are accessing the account via webmail access using a browser only with your computer - you are not using an email client on your computer such as Outlook or Outlook Express for accessing the account.

Have you tried deleting and recreating the account on your iPhone?

If no change after deleting and recreating the account and there is no error message provided, the only other suggestion I have is restoring your iPhone with iTunes as a new iPhone or not from your iPhone's backup. If you restore from your iPhone's backup, email account settings are included with your iPhone's backup.

Before doing that, try creating and accessing the account with Outlook Express on your PC - if you have Vista this will be with Windows Mail - the name change for Outlook Express with Vista. If you are unable to download new messages received at the incoming mail server with Outlook Express or with Windows Mail, something else is wrong which doesn't have anything to do with your iPhone.

I already answered this.

If no change after deleting and recreating the account on your iPhone, try restoring your iPhone as a new iPhone or not from your iPhone's backup followed by recreating the account. Email account settings are included with your iPhone's backup and if there is a problem with the email account settings included with your iPhone's backup, restoring from the backup will also restore the problem.