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How to fix error ‘421 Too many concurrent SMTP connections’ in cPanel and DirectAdmin servers

How to fix error ‘421 Too many concurrent SMTP connections’ in cPanel and DirectAdmin servers

Managing and troubleshooting mail servers forms a vital part of the Outsourced Website Support services we provide to shared server owners.

Among the common mail server errors, 421 is a common one that happens due to ‘too many concurrent SMTP connections’. This error usually denotes a high-traffic recipient mail server. (more…)