I've just spent an hour trying to set up an email address for our site using the wordpress article of the same name. All went quite well until it came to the 9th of the 10 steps.
Whilst this did create a CNAME record in the DNS, Google didn't seem to find it when I clicked on Verify.
However I eventually manually inserted the following line into the DNS record as generated by Google as one of their alternative methods. Note that they don't actually put the TXT prefix which is essential.
which was immediately recognised when I clicked on Verify.
Now maybe the propagation delay was the cause of my previous failures and it would have verified in any case, without the TXT line, but it's a coincidence that it all worked at this point.
Also, WordPress is not one of the hosts Google list, maybe you should talk to each other?