It is worth pausing on a fact that hides in plain sight: almost every online account you have offers a "forgot password" option, and almost every one of those sends the reset to your email. Your website host, your online banking, your social profiles, your suppliers' portals, the tools you run the business on - lose the password to any of them and the way back in runs through your inbox. That is convenient for you, but it carries a sharp implication. Whoever controls your main email account can, one by one, reset the passwords to nearly everything else and let themselves in, without ever needing to know your other passwords at all. The email account is not just another login; it is the master key.
This changes how you should think about that inbox. It is common to treat the email account as ordinary and reserve the careful passwords and extra security for the "important" things like banking. But the email is more important than most of them, precisely because it is the recovery route to all of them. A criminal who gets into your email does not just read your messages - they can begin quietly taking over your other accounts, and they can do it while covering their tracks, deleting the reset notifications so you do not notice until real harm is done. The very feature that makes your email so useful, that everything trusts it to prove who you are, is what makes losing control of it so serious.
The practical response is to protect your main email account as your single strongest login, treating it as the crown jewels rather than a utility. Give it a long, unique password that you use nowhere else, so that a leak from some unrelated website cannot hand over the keys. Turn on two-factor authentication here first of all, so that even a stolen password is not enough to get in. Be especially wary of anything that tries to trick you into entering your email login - a fake sign-in page reached from a link in a message is a favourite way in, and the email account is the prize worth the most effort to steal. And keep an eye on the account's own security: unexpected sign-in alerts, or password-reset notices for other services that you did not request, are early warnings worth acting on immediately.
A little structure helps too. It is worth making sure the email account's own recovery details - a backup email or phone number - are current and under your control, so you can get back in if you are ever locked out, and are not pointing at something a former employee or an old number could intercept. For a business, consider that if this one account is the master key, it should not depend entirely on one person being reachable; a sensible continuity plan knows how the business would regain access to its core email if the usual holder were unavailable. None of this is elaborate. It is simply recognising that of all the passwords you protect, the one guarding your email quietly protects all the others - and giving that inbox the defences its role deserves.