Regarding a specific thread going back and forth (span of a month or so, not years): Google marked as spam my 7th or 8th reply in a chain of emails with a pros

Regarding a specific thread going back and forth (span of a month or so, not years): Google marked as spam my 7th or 8th reply in a chain of emails with a prospective tenant (presumably) because my email contained instructions for sending me money. I assumed that they weren't interested anymore and had ghosted, but luckily we crossed paths at a grocery store or some such. My emails continued to be marked as spam after they added me as a contact, individually fished each one from their spam folder, and continued to write replies. Weeks later (with no apparent cause) I started arriving in their inbox again.