What is a mailbox provider? A Clear Guide

A mailbox provider (Gmail, Outlook, Yahoo) hosts recipient inboxes and decides whether your mail lands in the inbox, spam, or is rejected.

Why it matters

Knowing a mailbox provider helps you send mail that lands 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.