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ivan8
ivan8
Explorer
April 15, 2025
Solved

Fortimail - keep track of rejected mails due to excessive size

  • April 15, 2025
  • 6 replies
  • 2691 views

Hello,

 

Our Fortimail rejects emails which are too big

 

Is it possible to get a daily report with the rejected mails (from, to, subject, date) ?

 

Thanks for your help.

Best answer by ivan8

Dear Jean-Philippe,

Thank you for your prompt response.

After reading more about SMTP, I now understand that my initial request cannot be fulfilled directly.

Regarding your proposed solution:

As I understand it, before transmitting the email, the remote SMTP client announces the message size. At that point, FortiMail decides whether to accept or reject the transmission. Since the recipient address is not yet known at that stage, if the message is rejected, it is not possible to log the recipient address.

A possible workaround would be to accept all messages regardless of size, and then apply a Content Profile that redirects oversized messages to quarantine. Additionally, alert emails would be sent to the sender, recipient, or administrators, depending on the organization’s policy. This approach would allow us to retain a log of the event.

We plan to implement this solution in the near future, but have not tested it yet.

Thank you for your help and willingness to assist.

Best regards,

6 replies

Jean-Philippe_P
Staff & Editor
Jean-Philippe_P
Staff & Editor
April 18, 2025

Hello ivan8, 

 

Thank you for using the Community Forum. I will seek to get you an answer or help. We will reply to this thread with an update as soon as possible. 

 

Thanks, 

Jean-Philippe - Fortinet Community Team
Jean-Philippe_P
Staff & Editor
Jean-Philippe_P
Staff & Editor
April 22, 2025

Hello,

 

We are still looking for an answer to your question.

 

We will come back to you ASAP.

 

Thanks,

Jean-Philippe - Fortinet Community Team
Jean-Philippe_P
Staff & Editor
Jean-Philippe_P
Staff & Editor
April 23, 2025

Hello ivan8,

 

I found this solution, can you tell me if it helped you, please?

 

To generate a daily report of rejected emails based on size in FortiMail, you can follow these steps:

 

  1. Access the FortiMail Interface: Log in to your FortiMail web interface.

  2. Navigate to the Reporting Section: Go to the "Configuration" section where you can set up reports.

  3. Configure the Report:
    - Set the report name and select the time period for the report (e.g., "This week" or "Daily").
    - Choose the specific days for the report generation if needed.

  4. Select Report Content:
    - Ensure that the report includes details such as "from," "to," "subject," and "date."
    - You may need to customize the report to include specific filters for rejected emails due to size.

  5. Define Recipients and Notifications:
    - Enter the email addresses of the recipients who should receive the report.
    - Set up email notifications if required.

  6. Choose Report Format: Select the desired format for the report, such as "pdf" or "html."

  7. Schedule the Report: Set the report to run daily at a specific time.

  8. Save and Apply: Save the configuration and apply the settings. By following these steps, you can receive a daily report of rejected emails, including details like sender, recipient, subject, and date.
Jean-Philippe - Fortinet Community Team
    ivan8
    ivan8AuthorAnswer
    Explorer
    April 23, 2025

    Dear Jean-Philippe,

    Thank you for your prompt response.

    After reading more about SMTP, I now understand that my initial request cannot be fulfilled directly.

    Regarding your proposed solution:

    As I understand it, before transmitting the email, the remote SMTP client announces the message size. At that point, FortiMail decides whether to accept or reject the transmission. Since the recipient address is not yet known at that stage, if the message is rejected, it is not possible to log the recipient address.

    A possible workaround would be to accept all messages regardless of size, and then apply a Content Profile that redirects oversized messages to quarantine. Additionally, alert emails would be sent to the sender, recipient, or administrators, depending on the organization’s policy. This approach would allow us to retain a log of the event.

    We plan to implement this solution in the near future, but have not tested it yet.

    Thank you for your help and willingness to assist.

    Best regards,

      Jean-Philippe_P
      Staff & Editor
      Jean-Philippe_P
      Staff & Editor
      April 23, 2025

      Thanks for your answer, and I am glad it helps!

      Don't hesitate after implementing it to give your feedback and let us know if you are happy with the result!

      Jean-Philippe - Fortinet Community Team
      EmbertMorton
      EmbertMorton
      New Member
      May 30, 2025

      I ran into the same challenge when trying to audit oversized rejected emails in FortiMail. The workaround using quarantine and content profiles makes sense—at least it preserves event visibility. For broader reporting across campaigns, I’ve started using Phonexa, which gives me consolidated email tracking and rejection insights. It’s been really helpful for compliance and troubleshooting.

        filiaks1
        filiaks1
        Explorer III
        June 30, 2025

        Also external NAS could be an option Configuring mail data storage on a NAS server | FortiMail Appliances and Virtual Machines 7.2.0 | Fortinet Document Library 

          ivan8
          ivan8Author
          Explorer
          July 1, 2025

          Thanks for your input. I wasn’t aware that FortiMail could be configured to use a NAS server for mail storage. We’ve implemented the suggested solution—accepting all messages regardless of size, redirecting oversized ones to quarantine via a Content Profile, and sending alerts as needed. Mail storage is now a resource we must keep under control, and using a NAS server is an ideal approach.

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