For corporate support, that’s totally on them. Checking the spam folder is customer support. The “oh sorry your email went to spam!” is one of the few times I express dissatisfaction to a company. It’s not my responsibility to make sure my email doesn’t go to their spam folder. Not when I’ve taken all the right steps to make sure my emails are not marked as spam. If you have customers, you have to check your spam folder! It’s not foolproof.
You seem to not realize many email providers just drop emails (often after accepting it) instead of putting it in spam folders. So even your suggestion is of no help in that situation.
