I had an interview with a company yesterday. Today, when I wanted to ask the HRs for my interviewer's email address so I can send a thank-you note to them, both HRs that I've been in contact with during the process are out of the office until Tuesday due to Labor Day. So it is not likely that I will be able to send a thank you note until next Tuesday as I can't find their contact information anywhere.
Questions: Will a late thank-you note received as insincerely? If not, should I explain why I sent it late when I decide to send it? If yes, is there still a point of sending them then?
Additional note:
This is also a company that often not respond to the candidates in case of a rejection, so I mainly wanted to use a thank-you note as an opportunity to express my interest in this role and potentially asking for the next step of the process.