[wowtip]

It is a sad sign of the times, you can no longer (easily) set up an email server of your own and expect emails to be delivered to everyone.

Managing O365 for a few domains I quite frequently see mail from not-so-small companies with their own servers getting stuck in MS Quarantine filtering.

[a3_nm]

My email server is running on a cheap dedicated machine, with SPF and DKIM (and SSL) correctly set up, and which is only used to send my own email (no mass mailing, etc.). In many years of using this as my email system, I recall only two cases where my email was rejected: by a university, which required manual whitelisting; and by GMail once for an incomprehensible reason. Of course greylisting (delaying for a few hours the first time) is frequent, but that's fine. So I wouldn't say the picture is as grim as you suggest.

Maybe there were more cases where my mail got lost because of excessive filtering on other providers and where I didn't notice it, but there comes a point where I don't care and I can just blame the recipient if they use a provider which silently ignores some incoming mail...