I’ve checked twice by phone with the office to make sure I wrote down the accurate email address. It appears that when that period gets added, it gums up the works. Or else there’s some other voodoo going on that I don’t understand.
Could well be this. They might be running multiple email domains with some forwarding between the two. Businesses might often do that to capture emails accidentally typed wrong or as internal forwarding addresses to route email traffic to specific business units, etc.
It could be your email is getting through to the correct recipient, but some additional poorly configured internal routing is errantly returning an error externally when it shouldn’t be. It might pay to see if you get a response in a timely fashion before worrying too much unless your email is critical for some reason, in which case jump back on the phone.
I checked if unitedtalent.com and united.talent.com belong to the same company (so they would perhaps use the same email server infrastructure for both domains, which could give a server-side explanation for what you’ve seen) but that doesn’t seem to be the case. Therefore, it’s likely a client-side issue (or a “close server” issue, but since it seems to be Google, that sounds unlikely).
The first thing any email admin will tell you is to check sending from a different source. That could be another online tool if you want to try that. You’ll quickly narrow down if it is a problem on your side or their side that way. You can also do this via a raw telnet, but that’s complete overkill.
Beyond that, it isn’t uncommon for an organization to break up domain names internally, but you really shouldn’t see any of that except in email headers, if you are able to see them at all.
Since unitedtalent doesn’t seem to also own talent.com, there does appear to be an issue, and I would suspect their end, not gmail.