A recruiter scheduled a conference call with the lead Software Engineer for me, and I’d like to send the interviewer a thank you note. Would it be weird to message her on LinkedIn or find her email through a friend who works at the same company (they don’t know each other)? Should I send a card by mail instead?
I'm confused by the apparently popular sentiment of NOT sending a follow-up email after an interview. It's fairly common advice, and I've always done it. There are innumerable sites on the web that recommend the practice, which also gives you an opportunity to reinforce positive aspects of the interview. The portrayal of this as unwanted to obtrusive seems strange to me, given every person reading this has received some form of spam this week.
If you cannot find or do not have the email address, it is appropriate to send a thank-you through your recruiter. Normally, correspondence is done through your recruiter. This gives you an added layer of protection--hopefully most recruiters would not forward an email that is obviously not in your best interest.
Why would you do that?
I would highly prefer someone would not send me "useless" emails before I had any direct contact.
Considering the fact that it is very likely that she has more than one interview. Depending on the Company she probeply has more to do. She would be swamped with emails from People she might hire.
I personally would plainly refuse to give my emailadress to someone I might not hire.
You already stated that she is the/a Lead Software Engineer. She will more likely have a neutral or bad Response to such an email, than a good one.
When your call starts either tell them at the start of the call:
"I would like to thank you for taking the time for this interview".
Or you could do so at the end of the call: "Thank you for your time I hope to hear from you soon."
Anything else sounds weird to me (European) when an recruiter set the Meeting.
If you arranged the Meeting yourself just put the thank you in your confirmation email.
You could send a thank you note to your recruiter.