4 ms·
That's odd. I know that Spamassassin actually penalizes HTML and HTML only email. Are you sure there is not some sort of parasitic Bayes filtering happening he
by upofadown 5y ago
That's odd. I know that Spamassassin actually penalizes HTML and HTML only email.
Are you sure there is not some sort of parasitic Bayes filtering happening here?
- g_p 5y agoIt's very odd. I don't know how Microsoft implements their own server-side spam filtering, but the issue was coming from their filters. No issues with any other host. G Suite accounts received plaintext mail fine. I never found much by way of technical detail on 365 deliverability, beyond the usual DKIM/SPF/DMARC/PTR record guidance, and forms for getting yourself removed from the whitelist. What's especially strange is that this issue applied even when sending mail as a 365 subscriber. Once there was HTML content present in the email, deliverability (to other separate 365 tenants) improved! Very odd...