Proofpoint Essentials Standard and Encrypted Size Limits

Created by Abderrahim Ibnou el kadi, Modified on Wed, 26 May 2021 at 04:58 PM by Abderrahim Ibnou el kadi

SituationYou are having trouble sending/receiving emails with large attachments and wondering if Proofpoint Essentials enforces a limit on attachment sizes. 

This article provides information on the attachment size limit imposed by Proofpoint Essentials, and what to expect if that limit is exceeded. 

  • Standard Messaging  - 150MB Limitation
  • Encrypted Messaging - 35MB Limitation



Due to encoding, email programs can add up to 1/3 of the original attachment size to the message. Please keep this in mind when adding attachments.

Standard Messaging

Proofpoint Essentials supports email attachments up to 150MB in size by default. 

Many organizations will enforce a more stringent attachment size limitation on their mail server (sometimes as low as 10MB). If you are having problems sending/receiving emails with large attachments, it is most likely due to a restriction on your mail server or the recipient's server. 

You can create filters to impose size restrictions on inbound and outbound emails at both the Organization and User level. For more information on how to do so, please see our article on Creating a Filter.

Encrypted Messaging

Proofpoint Essentials encryption service does not use the same messaging gateway. The maximum file size when using encryption services is 35MB.

Total Email Size Versus Attachment Size

  • Attachments sizes can be seen on a computer when you view it's properties. 
  • Total Email Size is not the same size. Emails require the attachment to be encoded as part of the body. This encoding process will increase the size of the email up to 33% in most cases. 

For the total size to be 35MB, the actual attachment should not exceed 23MB. This is the safest amount when using Encryption.

What Happens To An Email That Exceeds The Limit

  • Standard - When a Standard email attachment exceeds the size limit, it will be hard bounced. 
  • Encrypted - When an Encrypted email attachment exceeds the size limit, it will be stuck in a queued state in the email message logs and will fail to be uploaded to the Encryption Portal.