@SaiHarshitha 

We have found multiple articles which tells us the exception SMTPAddressFailedException: 452 Too many recipients received

https://stackoverflow.com/questions/1338182/sendmail-error-452-too-many-recipients-received-this-hour https://confluence.atlassian.com/jirakb/jira-notifications-fail-occasionally-due-to-452-too-many-recipients-received-this-hour-215483685.html https://answers.microsoft.com/en-us/msoffice/forum/all/what-does-452-too-many-recipients-received-this/a81209bc-3a72-4ad5-b7f0-94866111bb63

The exception you're encountering is due to the SMTP server's limit on the number of recipients per hour. This is a server-side setting.

You can resolve this issue by requesting your email server administrator to increase the limit. Alternatively, you can adjust your application to distribute the sending of emails over a longer period to avoid hitting the limit.

The number of emails sent from Pega may vary based on the application users. Also, there is no limit from Pega in sending emails.

The limit is set at SMTP server side.

• When you send too many e-mails (or more often - a certain number of e-mails where a recipient does not exist) a destination mail server does not black list you, but instead they temporarily block access from your mail server (essentially the IP address of your mail server). This is called grey-listing. Usually this block is set for 1 hour but obviously can vary depending on the configuration.

• -Normally, "SMTPAddressFailedException: 452 Too many recipients received this hour" is thrown when breaching the anti-spam restriction of SMTP server regarding the maximum number of recipients that can be sent (from the SMTP server) for a specific domain in a defined time period. -Add more public IP addresses to your server

   IP Address of pega may be coming from Default Policy where the Limit is 2000.  You may need to add the Pega IP Addresses to Custom Policy and change the limit for 1 hour to 5000. If the same environment is being shared across Environments that increased the hits in an hour for send email to the Exchange server.

• You can do several things: -Contact the admins of the domain in question and request your IP address to be whitelisted. -Add more public IP addresses to your server

Please check on the above with the email server team for further clarification.

  See this article for further details:

what does " 452 Too many recipients received this hour, Please try later." mean

Solution:

Avoid  sending too much mail as your mail provider has you on a quota and you are exceeding it. You will need to work with the email server admin to resolve the issue.

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SMTP exception while sending emails using Agent