Knowledgebase: Inbound Mail Flow
Limits for sending and receiving email
Posted by Chris Moores, Last modified by David Szoke on 14 March 2018 02:59 PM

To ensure the ongoing health of our platform, Proofpoint Essentials imposes limits on the number of messages sent and received, the number of recipients per message and the size of a message.

Look at the messages below to identify your problem and learn ways to avoid these issues in the future.

  • You may see this message if you send more than 500 emails in a 10-minute period or if you send more than 2,500 emails in a single day.
  • When you get this error, you should be able to send mails again within 1 to 24 hours.

"The user you are trying to contact is receiving mail too quickly"

  • You may see this error the recipient's has received too much email. Your emails are only momentarily deferred and should be delivered without any additional actions.

"Too many recipients"

  • You may see this message if you send an email to more than 1,000 recipients in a single email.
  • When you get this error, you may need to send multiple emails in order to reach all recipients.

"Message size exceeds file system imposed limit"

  • You may see this message if you send an email that exceeds the recipients maximum file size.
  • When you get this error, you may need to find an alternate way to share the email contents with the recipient(s).

"Emails are being delayed or deferred"

  • You may see this error when the Essentials recipient has received the maximum allowed emails per minute. If a user is the subject of a large quantity of email being targeted at their address, we will process this over a longer period. 
  • Keep in mind that inbound limits are as follow:
    • For registered accounts is 200 messages in 60 seconds
    • For unregistered accounts (SMTP Discovery) in a domain there is a 500 message limit in 60 seconds (at the domain level).
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