SMTP Error 550 5.7.1

What This Error Means

This error indicates the receiving server rejected your email based on its security policies. This could be due to spam filtering, content policies, sender reputation, or authentication failures.

Common Causes

• 1Your IP or domain is blacklisted
• 2Email content triggered spam filters
• 3Missing or failed SPF/DKIM/DMARC authentication
• 4Sending to a restricted or protected mailbox

How to Fix It

• 1Check if your IP/domain is on any blacklists
• 2Review email content for spam trigger words
• 3Implement proper email authentication (SPF, DKIM, DMARC)
• 4Warm up your sending IP gradually