Message Size/Attachment Size Limit in Exchange Server 2016/2019

To change the message size limit in Microsoft Exchange Server, you can change the settings in Exchange Admin Center (EAC) or Exchange Management Shell (EMS)

Using Exchange Admin Center (EAC)

1. Log in to the Exchange Admin Center:

- Open a web browser and go to the URL of the Exchange Admin Center. https://<your-server-name>/ecp

- Log in with an account that has administrative privileges.

2. Navigate to Mail Flow:

- In the left-hand pane, select Mail Flow.

- Under Mail Flow, click on Send Connectors or Receive Connectors depending on whether you want to change the send or receive size limit.

3. Modify the Transport Settings:

- For send connector or receive connector, choose the relevant connector.

- In the Send Connectors section, click on the connector you wish to edit.

- In the details of the connector, locate Maximum message size or Maximum receive size.

- Set the desired size limit (in KB or MB). Exchange allows you to specify sizes between 1 KB and 100 MB.

4. Save Changes:

- Click Save to apply the changes.

For Specific Mailbox or User (for Receive/Send Limits)

If you need to modify the message size for individual mailboxes, follow these steps:

1. In the EAC, go to Recipients > Mailboxes.

2. Select the mailbox you want to modify.

3. Click the pencil icon (edit).

4. Under the Mailbox Features section, select Message Size Restrictions.

5. Set Maximum message size for both incoming and outgoing emails.

6. Click Save.

Using Exchange Management Shell (EMS)

You can also adjust the message size limit using PowerShell commands in the Exchange Management Shell (EMS).

PS Command to Change Maximum Send Size for Transport Configuration

Set-TransportConfig -MaxSendSize 50MB -MaxReceiveSize 50MB

This sets the maximum send message size to 50MB. You can adjust the size as required.

PS Command to Change Maximum Send Size for Send Connector

Set-SendConnector "Send Connector Name" -MaxMessageSize 50MB

This sets the maximum send message size to 50MB. You can adjust the size as required.

PS Command to Change Maximum Receive Size for Receive Connector

Set-ReceiveConnector "Receive Connector Name" -MaxMessageSize 50MB

This adjusts the maximum receive message size for a specific receive connector.

PS Command to Change Message Size for a Specific Mailbox

To modify the send and receive limits for a specific mailbox:

Set-Mailbox "Mailbox Name" -MaxSendSize 50MB -MaxReceiveSize 50MB

This will change both the maximum send and receive size to 50MB for that mailbox.

Considerations:

- Global Limits: Ensure the limits set at the server level (for Send/Receive connectors) are not being overridden by mailbox-level settings.

- OWA Limit (Exchange On-Premise) : OWA will not allow you to send 25 MB even if you set to 100 MB. Please use Outlook Application.

- Hybrid Environments: In hybrid environments with Exchange Online, you may need to configure limits via the Office 365 Admin Center or using PowerShell commands for Exchange Online.

That’s it! By following these steps, you should be able to change the message size limits for your Exchange Server as needed.