Postfix on home server with static IP

@calport i managed to let my home server sends email from my VPS i just set up the SMTP details but i still get blocked from yahoo, im just testing i don’t send much emails very few only for testing, i have issues with trying to configure SPF and DMARC and DKIM, i set up the right records in my domain name DNS manager but when i do check on these configurations through DNS checking websites, it says my SPF DMARC DKIM not set up, im missing something, i contact yahoo support and they did unblock my IP and sent me links where they explaining about setting up SPF DKIM, i managed to set these on the right way before while and still were getting blocked
i thought amazon is great company but this is the first time in my life i tried to rent service from them, i thought my problem will be fixed and no more emails issues, their price is good but i was shocked that there is 200 email limit per day and they don’t approve to increase that for all, even if we paying, that’s just not fair, and they responded to me the next day, and there is a paid support plans which i think is not good idea for such big company to have this kind of idea, all people must receive the same support as long as they are customers, some people don’t need support as long as their emails delivery is working without issues,
i found out that i can send 2000 email per day from free google SMTP, so people can send 60000 email per month free from any google email
i don’t know why all these companies are very strict about sending emails specially when the emails are not for marketing and not spam, just like my case , only notifications emails, only transactional emails like forgotten passwords, order confirmations and such, we are not sending bombs through emails , its just a text message LOL, and the funny part is i wonder how all these spammers manage to send emails without getting blocked, i receive spam daily since long time and from the same people, those who truly must be blocked not someone who run legit business,
i will try to inbox you @calport thank you so much for being really helpful , i appreciate that