https://docs.whmcs.com/9-1/tags/smtp-mail-provider/Recent content in smtp-mail-provider onHugo -- gohugo.iohttps://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/sender-verify-failed-errors/Mon, 01 Jan 0001 00:00:00 +0000https://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/sender-verify-failed-errors/Covers the “Sender Verify Failed” error during email sending or ticket reply importing, caused by a sending address that is invalid or missing on the SMTP server, with steps to cross-check cPanel Email Accounts against the Email Address field in General Settings > General, or the From Address in General Settings > Mail for ticket imports.https://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/smtp-authentication-errors/Mon, 01 Jan 0001 00:00:00 +0000https://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/smtp-authentication-errors/Addresses the “Could Not Authenticate” SMTP error caused by incorrect Mail Provider SMTP details in General Settings or by password hashing enabled on a Plesk server, with the fix of verifying SMTP settings and, on Plesk, switching Storing email passwords to Symmetric encryption under Tools & Settings > Security Policy.https://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/smtp-connection-errors/Mon, 01 Jan 0001 00:00:00 +0000https://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/smtp-connection-errors/Covers “Could not connect to SMTP host” and “SMTP connect() failed” errors, walking through five causes: incorrect SMTP host/port/SSL settings, blocked external mail connections (cPanel/Plesk fixes included), TLS certificate validation failures (with an SMTPAutoTLS workaround), DNS resolution failure, and firewall or expired-certificate blocks.https://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/smtp-password-command-failed-errors/Mon, 01 Jan 0001 00:00:00 +0000https://docs.whmcs.com/9-1/troubleshooting/troubleshoot-email/smtp/smtp-password-command-failed-errors/Explains the “SMTP ERROR: Password command failed: 535 5.7.139” error as a result of Microsoft removing basic username/password SMTP authentication in 2024, and directs reconfiguring the Mail Provider settings in General Settings > Mail to use Microsoft Entra app credentials instead.