Knowledgebase: Inbound Mail Flow
Acceptable Use Policy for Inbound and Outbound Email
Posted by , Last modified by David Szoke on 12 March 2018 08:13 PM

Why outbound limits?

As a committed anti-spam product, Proofpoint Essentials cannot condone the use of our platform to send out bulk mail.  Most users respect our fair usage policy and instead use dedicated email marketing systems to send out their bulk mail campaigns.  Unfortunately, there will always be a small number of users who, often unwittingly (via a compromised account), abuse the system and may end up affecting the quality of service we can provide for everyone.  Sending of spam through Proofpoint Essentials is strictly prohibited.

If a user has unwittingly had their account compromised (downloaded a spambot from the internet or been infected by malware/virus) and is sending out huge quantities of email, that user could inadvertently be putting the entire platform at risk of being throttled or blacklisted by outside entities.  By placing per-user limitations on Outbound usage, Proofpoint Essentials not only protects the system as a whole, but also the customer’s as well as the user’s reputation.

Why inbound limits?

Proofpoint Essentials has made changes (March 2018) to improve platform resiliency. It is important to our customers that we exceed stability and performance expectations, therefore we are expanding protection from mail bursts by introducing inbound throttling. If a user is the subject of a large quantity of email being targeted at their address (e.g. mailbomb at user level or directory harvest attack at domain level), we will process this over a longer period. Therefore, we reduce the immediate impact to our customer's local mail environment and ensure our platform can continue to exceed our stability and resiliency goals.

Outbound limits to control bulk mail abuse

In order to prevent the sending of spam and bulk mail through our system we have the following limitation in place:

  • Standard Users:  permitted to send out 500 emails over a 10 minute period or 2500 emails over a 24 hour period (All users are created by default as 'Standard Users').  If you have a business need to increase an account's limits, please see see this bulk KB article.
  • Bulk Sending Users: able to send out 2,000 in a 10 minute period, or 10,000 per day over a 24 hour period

The 24 hour time periods are reset at Midnight UTC (this applies to the 2500 and 10000 limits only).

What happens if a user reaches the outbound limit?

If a user hits the outbound sending limit within 10 minutes they will automatically be prevented from sending out any more email until their moving average of the past 10 minutes drops below the limit. When a user reaches the 10 minute limit, any messages sent beyond the limit will be bounced back to the sender.

Will these outbound consequences affect the entire organisation?

No, Proofpoint Essentials will not punish other users within an organisation because of the abusive usage or misfortune of one user.  Only the outbound abilities of the user responsible for sending the bulk mail will be affected.

Inbound limits:

For registered accounts is 200 messages in 60 seconds

For unregistered accounts in a domain there is a 500 message limit in 60 seconds (at the domain level).

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