What is A2P messaging? A Clear Guide

A2P (application-to-person) messaging is automated business SMS sent from software to people. Carriers require registration (10DLC, toll-free or short code) and treat unregistered A2P as spam.

Why it matters

Getting A2P messaging right keeps you compliant and lands more mail in the inbox. See the deliverability checklist.

How Rainmail helps

Rainmail sends from your own domain on a dedicated, isolated IP with SPF, DKIM, DMARC, reverse-DNS and managed warm-up handled for you, plus an AI watching list health and deliverability — and it welcomes senders SES, SendGrid and Mailchimp reject, from $8. Run the free checker or see plans.