SMTP Error 523, encountered in PHPMailer or Jenkins, indicates that the email size exceeds the recipient's email server limits. This can lead to delivery failure if the email surpasses the designated size threshold set by the server.

Cases Covered in SMTP Error 523:

SMTP Error 523 in phpmailer Instances & Examples:

• Case 1: "523 5.1.1 recipient@example.com: Email size exceeds the recipient's server limits. Please reduce the email size and resend."
• Case 2: "523 5.2.2 recipient@example.com: The recipient's mailbox is full. Delivery temporarily suspended."
• Case 3: "523 5.4.5 recipient@example.com: The recipient's email server is experiencing technical issues. Delivery delayed."
• Case 4: "523 5.7.1 Sender IP address is blocklisted. Email delivery denied. Please contact your email service provider to resolve the issue."

Causes of SMTP Error 523:

• SMTP error 523 arises when the size of the email exceeds the limits set by the recipient's email server.
• These limits, determined by the email server, dictate the maximum size accepted for incoming emails.

Solution to Resolve SMTP Error 523:

• Verify Email Server Limits: Before sending emails, it's crucial to check the size limits established by the recipient's email server. This information can be obtained from the email recipient or the server administrator.
• Ensure Compliance with Size Limits: To prevent recurrence of this error, ensure that all outgoing emails adhere to the specified size limits enforced by the recipient's email server.

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