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Managing mail flow in Exchange Server plays a vital role in effective database management. Heavy attachments in emails cause data to pile up and consume extra storage space. However, as a solution to this issue, it is possible to set email size limits within Exchange Server using Exchange Management Shell and Exchange Admin Center. But before that users should plan or consider some aspects related to the message size limits.

Why Exchange has a size limitation for email messages?

Microsoft limits the size limit for emails in Exchange Server due to several security reasons. In the absence of limitation, the server will receive many large email files and create a bottleneck situation in processing.

Problems related to maximum size limits

When an incoming email message reaches the pre-determined size limits, then it can cause many problems in the account. Some of the error message are following-

  • “552: Message size exceeds maximum permitted.”
  • “System Undeliverable, message size exceeds outgoing message size limit.”
  • “Attachment size exceeds the allowable limit.”
  • “The size of the message you are trying to send exceeds the global size limit of the server. The message was not sent; reduce the message size and try again.”
Considerations for setting message size limits
  • Maximum size limits on incoming and outgoing messages
  • Mailbox storage quota and maximum message size limits
  • Users who are allowed to use more than current specified message size limits for sending/receiving emails

Keeping these considerations in mind, let us understand how we can alter the default mail size limits in Exchange Server 2013.

Use of Exchange Management Shell to change the mail size limit

First, open Exchange Management Shell on your Exchange Server. Check the current server limit on emails by running the following cmdlets.

To check the Transport service emails limits, run this command:

get-transportconfig | ft maxsendsize, maxreceivesize

To check the Transport service emails limits

To check receive/send connector service email limits, run the following command:

get-receiveconnector | ft name, maxmessagesize

To check receive/send connector

NOTE: Use “send” in place of “receive” in cmdlet to check send connector service emails limit

Now to change the emails size received by the Transport service, execute the following cmdlet:

Set-TransportConfig -MaxSendSize 15MB -MaxReceiveSize 15MB

to change the emails size

NOTE: You can either increase or decrease message size limit using the above cmdlet.

Also, you can set limits for the results of the get-transportconfig cmdlets as:

get-transportconfig | Set-TransportConfig -maxsendsize 20MB -maxreceivesize 20MB; get-receiveconnector | set-receiveconnector -maxmessagesize 15MB; get-sendconnector | set-sendconnector -maxmessagesize 15MB; get-mailbox | Set-Mailbox -Maxsendsize 10MB -maxreceivesize 10MB

set limits for the results

NOTE: The above cmdlets do not consider if the attachments are included or not. Large messages with no attachments might stop immediately.

To set a Transport rule to avoid receiving attachments above a certain size limit (here 10MB) and to display a message, run the following cmdlet:

New-TransportRule -Name LargeAttach -AttachmentSizeOver 10MB -RejectMessageReasonText “Message attachment size over 10MB – email rejected.”

Set a Transport rule

Thus, you can make use of Exchange Management Shell to manage the email size limit of your Exchange Server. Let us have an easier way to set these limits, through the Exchange Admin Center.

Use of Exchange Admin Center to change the mail size limit

You can set a new rule form EAC as:

  1. To set a rule for large attachments, go to mail flow>rules and click create a new rule after expanding +.
    set a rule for large attachments
  2. In the rule page, enter the details like name, message, filter, and other options. After this, click Save.
    Save massage details

Exchange Admin Center allows setting the email size limit flowing into the server. To do this, perform the steps one-by-one:

  1. Navigate to Exchange Admin Center>mail flow>receive connectors>… (more) and click Organization transport settings.
Exchange Admin Center
  2. In organization transport settings, edit the values of Maximum number of recipients, Maximum receive message size (MB), and Maximum send message size (MB). Finally, click Save.
     organization transport settings

With these methods, you can manage Exchange data growth up to some extent. However, if you face issues like Exchange database corruption, you should try some tools that can recover data from EDB files.

Kernel for Exchange Server, an automated EDB Recovery tool for recovery and migration, works for recovering inaccessible EDB data to Outlook PST, Microsoft 365 and more destinations.

Summing Up

Exchange Server gets affected by the huge size of emails. We can solve this issue by changing the maximum limit of email sizes at different ends of mail flows. However, if you are facing issues due to the corruption of Exchange database files, you should recover data from the corrupt EDB files using an Exchange EDB file recovery tool like Kernel for Exchange Server. It repairs data efficiently and migrates it precisely to different destinations.

Kernel for Exchange Server
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