Custom domain with AppEngine and Firebase auth email templates

Question

I have an AppEngine app that uses Firebase auth to manage users.

I recently added a custom domain to the AppEngine app, and that worked fine.

Now I'm trying to manage the Password Reset template and change the sender email to match my domain. But when I follow the instructions to add the 2 TXT records and 2 CNAME records, the verification never completes. It's been in this state for almost 2 days. What am I doing wrong?

Instructions are:

Answer 1

Edit the DNS settings Firebase provided to match these patterns:

CNAME 1

HOST:   firebase1._domainkey
VALUE:  mail-YOURDOMAIN-com.dkim1._domainkey.firebasemail.com.

CNAME 2

HOST:   firebase2._domainkey
VALUE:  mail-YOURDOMAIN-com.dkim2._domainkey.firebasemail.com.

TXT 1

HOST:   @
VALUE:  v=spf1 include:_spf.firebasemail.com ~all

TXT 2

HOST:   @
VALUE:  firebase=YOURDOMAIN