Not at all my experience. I was sending paying customers emails with their license key and a link to our starting page for years and it was fine. Recently our emails randomly land in spam v even though:
-we have never sent one unsolicited email
-100% of those emails are opened and read (I know because customers are activating their licenses). It's hard to imagine anyone mark the email with license they paid several hundred dollars for as spam
-we get tons of engagement, we answer around 30-40 emails a day
Something is terribly wrong with Gmail spam filter recently. Some of the emails from my customers land in my spam folder as well. They more often than not don't contain any links or anything out of the ordinary. Just a simple question or two.
It started happening a few months ago. It's a huge pain. All Google support tells us is that their magical box they can't disclose thinks our emails are spam even though there is nothing suspicious about either our website, the link or the content of the email. They can't tell us what triggers the filter cause it will make the job of the spammers easier.
I am now left to play the game against spammers: they try to imitate legit emails, if they get close enough then my emails are similar to spam, I have to modify them in random way, then spammers catch up etc.
Yay for machine learning I guess. Doesn't work so well even you have an adversary trying to fool you.
Btw, we use Gmail and it's Gmail spam filter which is causing problems. Google analytics is able to guess our monthly revenue and number of licenses pretty well. We send exactly as many emails. We are paying customer of Google Suite. It's still not their problem that their magic box puts our emails in spam but it's all on us.