Solved! Comcast/Yahoo email migration

It's become clear that I'm not the only one who has run into a wall trying to complete the email migration. It's regrettable that Comcast didn't publicly provide its customers with the same excellent guidance offered by @XfinityEva.  For the past month, I've been trying to complete the migration to Yahoo as instructed by Comcast. Every attempt to use the link they provided failed, because after attempting to log in, I could never move beyond the login page. As a result, Yahoo's terms of service were never presented. Phone calls to Comcast customer service, including their escalation team, resulted in contradictory answers, no solutions and no acceptance of responsibility. I even tried doing it from Yahoo's side, but that also failed.

Last night, before seeing @XfinityEva's post, I discovered that Comcast/Xfinity has a standalone email export tool (her Option 2). It was very straightforward, although the export process took 2+ hours for 5,000 or so emails and contacts associated with one Comcast account. I went to bed before it completed, got up this morning and everything seems to have exported without issue. The export process created a new subfolder in Yahoo Mail and named it as my Comcast email address. My Comcast folder hierarchy was even preserved. I had previously created a Yahoo Mail account for a new email provider that uses Yahoo's "Currently" interface, which I was logged into. My Comcast email was exported directly into that. For the record, initially setting up Yahoo Mail for my new provider gave me 1 TeraByte storage, versus the 20 GB limit provided by Comcast.

Note: The above procedure, particularly regarding the increased storage limit, is most relevant if you, like me, are switching to a new email provider that already uses Yahoo's "Currently" system, and if you want to preserve your past emails. In that case, your storage is limited to what your provider offers. Whether you use a "Currently" participating provider, or If you choose to have a dedicated email account with Yahoo or another provider, that account must already exist in order to export your Comcast emails to it. If you want to continue using your Comcast email address, as provided for in Comcast's official migration instructions, this is not the solution for you.