Getting bounces from the server

Hi Priya1520,

the error code "550 5.7.1" is a common SMTP (Simple Mail Transfer Protocol) error that indicates a problem with email delivery. This can occur for various reasons:

• The recipient's email server may flag your message as spam.
• Security settings on either your organization's or the recipient's side could be blocking the email.
• Lack of permission to send emails to the recipient.
• Incorrect routing of the message to the wrong email server.

In your case, the error points to the IP address 23.251.230.83 being on a block list, likely due to past spam activity from that IP. To resolve this, contacting your Internet Service Provider (ISP) and requesting removal from the block list may be necessary. Checking your domain's SPF (Sender Policy Framework) entry is also advisable.

Fix NDR error 550 5.7.1 in Exchange Online - Exchange | Microsoft Learn