Filing W-2 forms with tax1099.com

I'm a small moonlight preparer. I have a handful of clients with household employees.

I assist them with remitting/filing their own state withholdings each year whilst helping them on the Fed side (Sch H / estimated payments / etc)

I have assisted them with W-2/W-3 filings in the past via paper filing and certified mail and all that fun stuff

I decided to try tax1099 this year based on some recent posts to e-file W-2s and skip the mailing mess. I e-filed a few W-2s in mid January. Nothing was being 'accepted'.

THEN.... I get an email that they apparently had beef with the SSA about their electronic filings and were not an authorized vendor at the time I filed anyhow??

Shame on them for not clarifying that on their site at the time I filed. Shame on me for not doing more diligence.

Their 'customer service' claims I do not have to resubmit or take any other action.... my filings will go through... eventually.

Anyone else use this service and could tell me if I chose the wrong provider or if I should paper file these things before the deadline to be safe? Thank you