can't access email from 3rd party app

I have not been able to access email from my Mac or iPhone using the Mac mail client. This started on the Mac on May 27th, and on the iPhone the issue started today.  On the iPhone, I have the message "the user name or password for "Comcast" is incorrect".  On the Mac, the error is "The following alerts are from the IMAP server for “Comcast”:Temporarily blacklisted IP Address - try again later".   My OS and iOS are up to date. I have checked the 3rd party email setting in my comcast email account (signed in via browser) and it is enabled. I have changed my password and rebooted.  I continue to get the error. I have seen others post that they have had this problem but I don't see a resolution posted. I am a former customer so not an active customer.  Any help you can provide would be appreciated.