Two things you should check on email...netmail.verizon.net > options > block senders > ensure the domains you are not receiving emails from have not inadvertantly been blacklisted for your account.
Also, VZ is using "right side verifiication" to reduce spam...if your visit 'http://network-tools.com you can do an email validation test on the email address you are not receiving from...
If the validation test fails, no verizon customer is receiving emails from that domain until the domains admin changes their email server to reply to validation requests...
playnic.com does rightside verification as illustrated by 'http://network-tools.com/default.asp?prog=validate&Netnic=whois.arin.net&host=support@plaync.com
So by calling tech support and having them submit the domain for inclusion on the safe list you've done about all that can be done at this point...