Fix "550 5.7.1": Message was rejected by the receiving server for a policy reason

If your email is bouncing with 550 5.7.1, it means message was rejected by the receiving server for a policy reason. Here is exactly what causes it and how to fix it.

What 550 5.7.1 means

This is the most common hard rejection. It usually means one of three things: your sending IP or domain is on a blocklist, your message failed authentication (SPF/DKIM/DMARC), or the content tripped a spam or policy filter.

How to fix 550 5.7.1

• Check your domain and IP against major blocklists (Spamhaus, Barracuda, SORBS).
• Confirm SPF, DKIM and DMARC all pass for the exact From domain.
• Warm up a new IP slowly and cut spammy content, shorteners and risky links.

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 that watches your list health and deliverability. It also welcomes the senders Amazon SES, SendGrid and Mailchimp reject — from $8, cheaper per email than SES. Run the free 10-second checker or see plans.