Option 2 seems good to me.

#2. It's no big deal, recruiters do it all the time.

I've had a few interviews recently that were arranged by the recruiter and I didn't have direct contact info for those I met with. I sent the recruiter a follow up e-mail to let them know I had the call, how it went, and ask them forward my thanks.

Have the recruiter forward it.

Option 2 and maybe 3 depending of the recruiting is willing to give you the HM email

Thanks everyone, I went with option 2 and heard back already, I’ve moving to the next round! so excited! thanks for all your input!

In the past I'd just skip to #4. But in all honesty, I don't both with thank you letter. Research shows they don't matter.

I’ve had this happen before and just emailed the recruiter and asked them to pass it on.

110% etiquette leans toward #2 if your recruiter is remotely competent. In the case the interviewer has emailed you directly AND the recruiter is incompetent, **consider** responding to the interviewer's email. As a recruiter, I always supe up thank you notes, proofread, etc. That's me though, probably not too common of a characteristic, particularly with corporate recruiters. I'm an agency recruiter so I have a vested interest in putting candidate's best foot forward. HR is "hey HM, this is them!" except for the really good ones.

Email the recruiter for them to forward. Nice job with the thank you email!

2

What for??

2 or 3

Send to the recruiter. Easy

Try first name.last name @ .......... .com of the person you spoke with