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Summary: Exchange Server 2013 allows managing size limit of a message and its individual components. It helps in improving efficiency of data storage. Here, we will learn why Exchange has size limits, considerations for setting them, and how to increase size limits. Furthermore we will also explore data recovery tool, Kernel for Exchange Server recovery to handle database corruption.

Effective mail flow within Exchange Server is essential for maintaining a competent database system. The accumulation of large attachments in emails causes unnecessary storage consumption. Fortunately, there are solutions available to address this concern. By configuring email size limits through the Exchange Management Shell and Exchange Admin Center, administrators can efficiently control the volume of data. However, it’s imperative to meticulously plan and consider various factors related to message size limits before implementing these changes.

Types of message size limits

  • Message header limit: The email message header contains information about the email route, sender, recipient, and whether the message is spam or found with viruses.
  • Message size limit: You can define the limit on incoming and outgoing email messages. The limit includes the total message size, including header, body, and attachment.
  • Attachment size limit: Defines the size of individual attachments only. A message can have more than one attachment affecting the overall size of a message.
  • Recipient limit: Allows limiting the number of recipients you can send messages to and are mentioned in To, Cc, and Bcc of an email.
Why does Exchange have a size limitation for email messages?

When a mailbox is created, there is no limit on the size of messages that users can send or receive. Microsoft allows you to manage the size limit for emails in Exchange Server due to several security reasons. In the absence of limitations, the server will receive many large email files and create a bottleneck situation in processing.

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

  • “552: Message size exceeds the maximum permitted.”
  • “System Undeliverable, message size exceeds the 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 the 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 email 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 the cmdlet to check send connector service emails limit

Now, to change the size of the emails 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 the 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 stop attachments from receiving above a specific 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

Redefine size in individual mailboxes

  1. In the EAC, navigate to Recipients > Mailboxes.navigate to Recipients Mailboxes
  2. In the user mailboxes, click the one you want to increase email size limit in Exchange Server, and then click Edit.
  3. On the mailbox properties page, click Mailbox.Increase email size limit in Exchange Server
  4. Under Message Size Restrictions, click Manage message size restriction to view and increase the message size limits.Increase the message size limits
  5. Click Save to make your changes.

You can set a new rule from 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. On the rule page, enter the details like name, message, filter, and other options. After this, click Save.
    Save massage details

The 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 the Maximum number of recipients, Maximum receive message size (MB), and Maximum send message size (MB). Finally, click Save.
     organization transport settings
Finding ways with the Exchange Server Recovery tool

With these methods, you can manage Exchange data growth to some extent. Managing the server to retain the Exchange mailboxes is often a costly procedure. Increasing the storage space will help to accommodate more email messages, but with time, it will start exceeding the limit. Due to this, you’ll increase the limit again.

It is better to take backups of your mailbox database or delete items from the mailboxes that are not needed further. This will help you save cost, time, and resources. However, if you face issues like Exchange database corruption, try some tools that can recover data from EDB files.

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

Summing up

During large email communication, Exchange Server often faces challenges. A feasible solution to this would be managing the maximum email size limit in the mail flow. This can be done either with Exchange Admin Center, Exchange Management Shell, or using reliable third-party tool, Kernel for Exchange Server. Using this utility would help repair damaged data and supports precise migration.

Kernel for Exchange Server