Error 521 Does Not Accept Mail – Causes and Fixes
It does not accept mail. The recipient mail server does not actually accept and deliver email itself. Therefore, emails can...
SMTP
Simple Mail Transfer Protocol Error Codes
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Error 523 Size Exceeds Server Limits – Causes and Fixes
The total size of your mailing exceeds the recipient server limits. Causes Recipient mail server does not acknowledge email with... -
Error 530 Authentication Problem – Causes and Fixes
Mostly is an authentication problem. However, sometimes it may just be the recipient server blacklisting yours or it is just... -
Error 541 Rejected Message – Causes and Fixes
The recipient address rejected your message. Your message has been labeled and detected as spam mail or blocked for any... -
Error 550 Non-Existent Email Address – Causes and Fixes
Non-existent email address. The destination mail server was unable to verify the email address used. On the other half, the...