SMTP Error 530, encountered in PHPMailer or Jenkins, signifies authentication failures, access denial due to sender IP restrictions, or lack of domain verification during the email sending process. This error denotes issues with authenticating or verifying the sender's credentials, resulting in email delivery rejection.

Cases Covered in SMTP Error 530:

SMTP Error 530 in phpmailer Instances & Examples:

• Case 1: "530 5.5.1 Invalid username or password. Authentication failed for sender@example.com."
• Case 2: "530 5.5.2 Access denied. Sender IP address is not allowed to send emails. Please contact the administrator."
• Case 3: "530 5.7.0 Authentication required. Please authenticate before sending emails."
• Case 4: "530 5.7.1 Sender domain is not verified. Email rejected due to lack of domain authentication."

Causes of SMTP Error 530:

• SMTP error 530 occurs when there is a problem with the client's authentication process with the sender's email server.
• In rare instances, this error may occur if the sender's IP address is listed in a public or private blocklist.

Solution to Resolve SMTP Error 530:

• Verify User Credentials: Ensure that the user credentials used for authentication with the email server are accurate and free from syntax errors.
• Check for IP Address Blocklisting: Confirm whether the client's IP address is listed in any blocklists. If so, users can initiate an appeal process to have the IP address removed from the blocklist(s).

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