The 0.3% rule: what a spam complaint rate really measures
Google and Yahoo publish 0.3%, but measure it differently. Amazon SES's own limit is 0.1%, and Gmail's complaints never reach your suppression list.
Google and Yahoo publish 0.3%, but measure it differently. Amazon SES's own limit is 0.1%, and Gmail's complaints never reach your suppression list.
A bounce is an SMTP status code, not a label. What 5xx and 4xx actually mean, where the hard/soft split breaks down, and what to suppress versus retry.
Gmail and Yahoo require RFC 8058's List-Unsubscribe-Post header, not just a link in the footer. The exact header form, why GET fails it, and where Microsoft differs.
A new domain has no history with mailbox providers. Start with your most engaged contacts, raise volume gradually, and watch the two metrics that tell you it's working.
Mailbox providers score your whole list as one reputation, so cold subscribers cost your engaged ones too. How to define cold, re-engage, then remove the rest.
Promotions is a Gmail filing tab, not the spam folder. What actually decides placement, and how to tell it apart from a real deliverability problem.
SPF, DKIM, DMARC and MAIL FROM: what each DNS record looks like, exactly where it goes, and how to check it with dig.
SPF checks the sending server, DKIM checks the message, and DMARC ties both to the address your reader actually sees. How the three fit together.
Gmail, Yahoo and Microsoft each demand authentication and a 0.3% spam cap from bulk senders. What each one actually says, quoted, and where they don't agree.
Deliverability is a reputation you build, not a setting you switch on. What SPF, DKIM and DMARC prove, the bulk sender rules, and the thresholds that matter.