Resources
Our guides cover four critical areas of email infrastructure: platform and protocol configuration, including documented limits; standards, compliance, and consent requirements that govern what you can send and measure; infrastructure decisions that determine how email is sent and delivered; and failure analysis to help you understand what happened when a message doesn't reach its destination. Every guide is grounded in primary sources from the platform provider, regulator, or standards body itself.
The four ways to send application email through Microsoft 365, what each one actually allows, and the limits Microsoft documents for them.
Read the guideThe difference between the SMTP relay service, Gmail SMTP and restricted Gmail, with Google's documented limits for each.
Read the guideWhat the header does, how RFC 8058 one-click unsubscribe works, and exactly what Google, Yahoo and Microsoft each require of bulk senders.
Read the guideWhat double opt-in is, what GDPR actually requires, and why automated security scanners confirm subscriptions nobody agreed to.
Read the guideWhich tracking-pixel purposes need consent under the EDPB guidelines and the CNIL recommendation, and the narrow deliverability lane that does not.
Read the guideHow warming works, why domain reputation now matters more than IP reputation, and why automated rate limits beat a manual schedule.
Read the guideWhy a dedicated IP fails for senders with spiky volume, how a shared pool stays warm, and the test that decides which one you need.
Read the guideWhat ports 25, 465, 587 and 2525 are each for, why outbound 25 is blocked almost everywhere, and which one to configure.
Read the guideHard versus soft bounces, how to read an SMTP bounce code, why the code is sometimes wrong, and what to do about the bounces nobody can parse.
Read the guideHow the four authentication standards fit together, why alignment matters more than any single record, what DMARCbis changed in 2026, and where DKIM2 actually stands.
Read the guideWhat BIMI is and is not, the DMARC policy it requires before any logo appears, the record and SVG format, VMCs versus CMCs, and which mailbox providers actually show the logo.
Read the guideThe full developer documentation, including every SMTP header and API endpoint, lives at omnivery.com/docs.