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ActiveSync attachment limits in Exchange 2019

shimaa sherif 41 Reputation points
2026-02-02T09:14:28.8666667+00:00

On-prim Exchange 2019 CU 15 server.

When trying to send email from Outlook for android devices with large attachment , we got an error :

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EasSendFailedPermanentException: An EAS Send command failed: Unable to send the message: either the send quota has been exceeded; or the message was too large; or the mailbox is over-quota. Exchange ActiveSync error details: SendQuotaExceeded, Code ='115'. --> Unable to send the message: either the send quota has been exceeded; or the message was too large

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Exchange | Exchange Server | Management
Exchange | Exchange Server | Management

The administration and maintenance of Microsoft Exchange Server to ensure secure, reliable, and efficient email and collaboration services across an organization.

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Kha-N 8,260 Reputation points Microsoft External Staff Moderator
2026-02-02T10:14:48.39+00:00

Hi @shimaasherif,

Welcome to Microsoft Q&A, and thank you very much for reaching out.

Based on your description, aside from the Q&A assist suggestions, may I confirm the exact attachment size that you were trying to send through Outlook for Android?

As I checked, In Exchange 2019, ActiveSync does not include a specific maxAllowedContentLength entry in the Microsoft‑Server‑ActiveSync web.config by default. Instead, ActiveSync relies on the global IIS maxAllowedContentLength value, which applies to all websites on the server. The default IIS limit is 30000000 bytes. If the WBXML‑encoded ActiveSync request exceeds this threshold, the device will return SendQuotaExceeded, Code='115' error.

If the attachment exceeds this limit, you can adjust the content length limit by following these steps:

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For more details, you can check this Microsoft documentation here.

Please also note that ActiveSync adds overhead because each message is wrapped in WBXML. As a result, the actual payload sent to the server is larger than the original file. Microsoft recommends setting the limit to roughly 33% higher than the maximum message size you want to allow to account for overhead.

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I hope this helps.

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  1. AI answer

    2026-02-02T09:14:39.3533333+00:00

    The error message you are encountering indicates that the email you are trying to send exceeds the allowed limits set for your Exchange ActiveSync configuration. Here are a few steps you can take to troubleshoot and potentially resolve the issue:

    1. Check Message Size Limits: You need to verify the maximum message size limits configured in your Exchange environment. You can do this by running the following PowerShell command: 
         Get-TransportConfig | fl *size
      Ensure that the MaxSendSize is greater than the size of the attachment you are trying to send.
    2. Modify Exchange ActiveSync Settings: If the maximum message size is not sufficient, you may need to increase it. This can be done by modifying the ActiveSync settings in the web.config file for the Exchange server. Look for the MaxDocumentDataSIze and MaxRequestLength settings and adjust them accordingly.
    3. Check ActiveSync Mailbox Policy: Verify the ActiveSync mailbox policy assigned to the user. You can retrieve the policy settings using: 
         Get-ActiveSyncMailboxPolicy (Get-Mailbox alias).ActiveSyncMailboxPolicy | ft name,*Attach* -AutoSize
      Ensure that the MaxAttachmentSize is set to a value that accommodates the size of the attachments being sent.
    4. Send Quota: The error message also mentions that the send quota may have been exceeded. Check the mailbox quota settings and ensure that the user has not exceeded their limits. You can check this with: 
         Get-Mailbox <UserAlias> | fl ProhibitSendQuota,ProhibitSendReceiveQuota
    5. Big Funnel Delay Item Size Threshold: If you have recently increased the message size limit, ensure that the BigFunnelDelayItemSizeThreshold limit is also increased. This can be done using the New-SettingOverride cmdlet.

    By following these steps, you should be able to identify and resolve the issue with sending large attachments via Exchange ActiveSync.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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