depends, If you ignore all the outgoing things, like SPF, DKIM, DMARC, etc. Your outgoing emails will always go into spam or disappear completely.
If you follow all the outgoing things but ignore the inbound mail checking, you will get quite a bit of spam. I run my own email server and instead of blocking bad incoming emails I just send then to the spam folder. I usually receive about 2-4 spam email a day, usually it's just marketing crap or it's a single link with some cutout of a wikipedia article to avoid spam detectors, and sometimes it's trying to extort you. I find it fun to read them sometimes, one time I got an email saying I missed a payment for my domain name but they got the amount of VAT wrong AND the maths on the subtotal. Some of them are comicality bad. but not quite the flood you might expect. If more people where on my email server or if I signed up to any shitty website I came across I'm sure it would be a lot worse though.