It can be really frustrating — particularly if you send big attachments on a regular basis — if your email prevents you from sending attachments over a certain size. Fortunately, the Exchange Admin Center lets you increase the maximum attachment size that you can send on an email.
Follow the steps outlined below to increase the maximum attachment size limit in Exchange Admin Center [Classic]:
- Navigate to Microsoft 365
- Select Admin on the app launcher
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
- Under recipients, click mailboxes
- Click the 3 horizontal dots and click Set default message size restrictions
- Choose your message size restriction and then click OK
The process differs slightly if you are using the new Exchange Admin Center. If you followed the process outlined above and couldn’t follow each step because sections seemed to be missing, you’re probably using the new EAC. In that case, follow the steps outlined below.
- Navigate to Microsoft 365
- Select Admin on the app launcher
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
- Under recipients, click Mailboxes
- Click Set default message size restrictions
- Choose your message size restriction and then click Save
Remember, this changes the default message size restriction for your entire organization. You can also modify these settings on a mailbox-by-mailbox basis, should you wish. I’ll demonstrate how you can do that later in the blog post too.
Step-By-Step Process [With Screenshots]: Increase Maximum Message Size Limit In Exchange Admin Center [Classic]
If you are using the classic version of the Exchange Admin Center, you can follow the steps outlined below to increase the maximum message size limit.
- Navigate to Microsoft 365
- Select Admin on the app launcher
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
- Under recipients, click mailboxes
- Click the 3 horizontal dots and click Set default message size restrictions
- Choose your message size restriction and then click OK
Here’s a walkthrough complete with screenshots to make the process as easy as possible.
- Navigate to Microsoft 365
First things first, you need to navigate to Microsoft 365. There are numerous ways that you can do this using a variety of URLs. Some of the URLs you can use include:
- Microsoft365.com
- Microsoft.com
- Portal.office.com
- Office.com
All of these links will bring you to the Microsoft 365 home screen, which is where you need to be to begin the next step.
Once you’ve followed one of the URLs above, ensure you have your Microsoft 365 credentials to hand and sign in.
- Select Admin on the app launcher
Once you’re logged into Microsoft 365, use the app launcher to open up the Microsoft 365 Admin center.
To access and use the Admin section of Microsoft 365, you must have the appropriate permissions. If you’re not an administrator within Microsoft 365, you’ll be unable to complete the process outlined here.
If you’re not a M365 admin — if you can’t see the Admin application indicated in the second screenshot above — you need to speak to whoever set up your Microsoft 365, or the person/company that manages it for you. They can grant you admin permissions or, alternatively, complete this process for you.
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
Again, you must have the correct permissions to access and use the Exchange admin center. Once you have clicked Exchange in the list above, you should see a screen similar to one of the two screenshots below.
The screenshot on the left is the classic Exchange admin center, whereas the screenshot on the right is the new Exchange admin center. If your screen looks like the one on the right — the new Exchange admin center — click here to jump to the step-by-step process for increasing message size limit in the new EAC.
- Under recipients, click mailboxes

- Click the 3 horizontal dots and click Set default message size restrictions
- Choose your message size restriction and then click OK

Following the process outlined above, the default message size restriction will be changed for all of your mailboxes.
As you may have seen in the screenshot above, you can change the message size restriction for individual mailboxes. If that’s something you want to do, click here to be taken to instructions on how to increase maximum message size limit — for individual mailboxes — in the Exchange admin center.
Step-By-Step Process [With Screenshots]: Increase Maximum Message Size Limit In Exchange Admin Center [New]
If you are using the new version of the Exchange Admin Center, you can follow the steps outlined below to increase the maximum message size limit.
- Navigate to Microsoft 365
- Select Admin on the app launcher
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
- Under recipients, click Mailboxes
- Click Set default message size restrictions
- Choose your message size restriction and then click Save
Here’s a walkthrough complete with screenshots to make the process as easy as possible.
- Navigate to Microsoft 365
First things first, you need to navigate to Microsoft 365. There are numerous ways that you can do this using a variety of URLs. Some of the URLs you can use include:
- Microsoft365.com
- Microsoft.com
- Portal.office.com
- Office.com
All of these links will bring you to the Microsoft 365 home screen, which is where you need to be to begin the next step.
Once you’ve followed one of the URLs above, ensure you have your Microsoft 365 credentials to hand and sign in.
- Select Admin on the app launcher
Once you’re logged into Microsoft 365, use the app launcher to open up the Microsoft 365 Admin center.
To access and use the Admin section of Microsoft 365, you must have the appropriate permissions. If you’re not an administrator within Microsoft 365, you’ll be unable to complete the process outlined here.
If you’re not a M365 admin — if you can’t see the Admin application indicated in the second screenshot above — you need to speak to whoever set up your Microsoft 365, or the person/company that manages it for you. They can grant you admin permissions or, alternatively, complete this process for you.
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
- Under recipients, click Mailboxes

- Click Set default message size restrictions

For me, Set default message size restrictions appears as soon as I come onto the Mailboxes page.
If it isn’t appearing for you, try refreshing your page and clearing your cache for the Exchange admin center and it should appear.
- Choose your message size restriction and then click Save

Choose maximum size [up to 153600 KB [roughly 153MB] which is Microsoft’s restriction] and then click Save.
This change will be applied to all new mailboxes that you create for your organization.
If you’d rather change maximum message size limit for a few individual mailboxes, follow the step-by-step process outlined in the next section of this blog post.
Step-By-Step Process [With Screenshots]: Increase Maximum Message Size Limit In Exchange Admin Center [For Individual Mailboxes]
If you want to change message size limits for individual mailboxes rather than your entire organization, you can follow the steps outlined below.
- Navigate to Microsoft 365
- Select Admin on the app launcher
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
- Under recipients, click Mailboxes
- Select a mailbox from the list
- Click Manage mail flow settings
- Click Edit next to Message Size Restriction
- Set the limits and then click Save
I’ve included screenshots below to give you a comprehensive walkthrough of the entire process.
- Navigate to Microsoft 365
First things first, you need to navigate to Microsoft 365. There are numerous ways that you can do this using a variety of URLs. Some of the URLs you can use include:
- Microsoft365.com
- Microsoft.com
- Portal.office.com
- Office.com
All of these links will bring you to the Microsoft 365 home screen, which is where you need to be to begin the next step.
Once you’ve followed one of the URLs above, ensure you have your Microsoft 365 credentials to hand and sign in.
- Select Admin on the app launcher
Once you’re logged into Microsoft 365, use the app launcher to open up the Microsoft 365 Admin center.
To access and use the Admin section of Microsoft 365, you must have the appropriate permissions. If you’re not an administrator within Microsoft 365, you’ll be unable to complete the process outlined here.
If you’re not a M365 admin — if you can’t see the Admin application indicated in the second screenshot above — you need to speak to whoever set up your Microsoft 365, or the person/company that manages it for you. They can grant you admin permissions or, alternatively, complete this process for you.
- Navigate to the Exchange Admin Center by clicking Show all and then Exchange
- Under recipients, click Mailboxes

- Select a mailbox from the list

Choose the mailbox from the list that you want to edit message size restrictions for. In this example, we’re going to edit the maximum message size for Bob’s inbox.
- Click Manage mail flow settings

- Click Edit next to Message Size Restriction

- Set the limits and then click Save

And voila! The process is now complete. The mailbox you’ve edited will have the higher maximum message size that you set here almost instantly, although you might need to relaunch Outlook to encourage the changes to synchronise quickly.
I hope you’ve found this blog post helpful! If you have any questions, please feel free to leave a comment below and we’ll try to help out!
FAQs
How do I increase the maximum attachment size in Exchange? ›
Change attachment size limit in Exchange Admin Center
icon in the toolbar and click Organization transport settings. What is this? Change Maximum receive message size (MB) and Maximum send message size (MB) to 20. Click Save.
Admin Center>> recipients>> mailboxes, here you need to select a user's mailbox. Then click on the edit icon>> message Size Restrictions>> click view details and specify the maximum message size.
How do I increase attachment limit in Office 365? ›- Open Exchange Admin. Once logged in to your Office 365 portal click on Admin on then left menu bar and then Exchange to open the Exchange Admin.
- Open the Recipients Mailbox Properties. ...
- Change the Message Size Limit. ...
- Change the Maximum Message Size.
- Launch the EMC (Exchange Management Console).
- Expand "Organization Configuration" and select "Hub Transport".
- Select the "Send Connectors" tab in the middle pane.
- Right-click on the send connector to be modified and select Properties.
- Change the "Maximum message size (KB):" and click OK.
Increase mailbox size in Microsoft 365
There are two ways to increase the max mailbox size for a user: Assign an Exchange Online Plan 2 license to the mailbox. This will increase the mailbox storage limit from 50 GB to 100 GB. Enable Exchange Online Archiving.
On the Global Settings tab, select Transport Settings. In the Transport Settings section of the Actions pane, select Properties. On the General tab in the Transport Settings Properties dialog box, configure the value for Maximum send size (KB). Select OK.
What is the maximum file size for email? ›Email client | Sending and inbound size limits |
---|---|
Gmail | 25 MB |
GMX | 50 MB |
Outlook/Office 365 | 20 MB (10 MB for Exchange accounts), with up to 150 MB in Office 365 |
ProtonMail | 25 MB |
By default, the attachment size limit in Microsoft (Office) 365 is 50 MB. If you need to send a file via email that is larger than 50 MB, you will need to use a different method, such as a listserv or the SendTo application, in order to send the message.
What is the size limit of an Exchange Online mailbox? ›Outlook accounts can have up to 100GB of storage per mailbox (Exchange Online mailbox storage limits).
How do I send large files with Office 365? ›Click File > Info. Under the Image Attachments section, select Resize large images when I send this message. Return to your message, and click Send.
How can I send more than 25mb in Outlook? ›
If the file size is more than 25 MB, you will see “Oops, this email has over 25 MB of files attached. To send these files, please use SkyDrive” message. The best thing is that you can still send your huge file by uploading it SkyDrive. One can upload the file to SkyDrive without leaving Outlook.com.
What is the max file size for Outlook? ›Sadly, due to mail server restrictions, all versions of Outlook and Office 365 all have a default max attachment size limit of 20 to 25 megabytes (MB).
How do I change the attachment size limit in Exchange 2013? ›Navigate to Exchange Admin Center>mail flow>receive connectors>… (more) and click Organization transport settings. 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.
How do I change the attachment size limit in Exchange 2010? ›How to change the maximum send size for attachments using Microsoft ...
How do I check my recipient limit in Exchange 2016? ›To see the values of these limits, run the corresponding Get- cmdlet for the recipient type in the Exchange Management Shell.
How do I find mailbox size in Exchange Admin Center? ›- From the Exchange admin center, click mailboxes under recipients.
- Select the user whose mailbox size you want to check.
- Click the edit icon (looks like a pencil).
- Select mailbox usage.
There is not a way to increase past the 50gb limit but you can manage your emails by creating Archives or saving your email attachments to onedrive.
How do I increase mailbox quota in Office 365 PowerShell? ›- Connect to Exchange Online PowerShell.
- Run the following PowerShell cmdlet: PowerShell Copy. Get-Mailbox | Set-Mailbox -ProhibitSendQuota <Value> -ProhibitSendReceiveQuota <Value> -IssueWarningQuota <Value>
Gmail lets you send files or photos larger than 25MB. Users can use Google Drive to send larger files through Gmail. One can also use WeTransfers to send up to 2GB files.
How do I fix the Outlook data file has reached the maximum size? ›You can try compacting the data file: Go to File tab > Account Settings > Account Settings > Data Files tab, double click on the data file > Under General tab, click on the Compact Now button -> OK.
How many attachments can I send in an email? ›
Gmail allows you to send attachments up to 25MB per email. You can send multiple attachments in an email, as long as they do not add up to 25MB. If your attachment exceeds the 25MB limit, Google will automatically upload the file to your Google Drive and include a link instead of an attachment.
How do I fix 552 size limit exceeded? ›Answer: To resolve this error, you will need to adjust the settings on your MTA (Mail Transfer Agent) or Transport Hub. Microsoft Exchange users should see the Microsoft support article Message size limits in Exchange Server for assistance or contact your vendor.
How do I get around 25 MB attachment limit? ›Use Google Drive
If the Gmail email window detects that your attachment is larger than 25MB, the attachment is instead uploaded to your Google Drive account. A link to the file in Drive is then inserted into the email, and the recipient clicks the link and downloads it from Drive.
You use maximum to describe an amount which is the largest that is possible, allowed, or required.
How do I change the attachment settings in Outlook 365? ›Once Outlook is loaded and you are in your Inbox, click the gear icon in the top-right corner, which is your settings. Click View All Outlook Settings → Attachments. Under Sharing Preferences, you can select from several different options.
What do I do when my Outlook storage is full? ›...
Here are some ways to keep your mailbox size under control:
- Archive older items – Move old items you want to keep to an archive. ...
- Empty the Deleted Items folder – Empty the Deleted Items folder frequently to make sure you aren't keeping messages you don't need.
How to change the maximum send size for attachments using Microsoft ...
How do I change the attachment size limit in Exchange 2013? ›Navigate to Exchange Admin Center>mail flow>receive connectors>… (more) and click Organization transport settings. 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.
Why is there a limit on email attachment size? ›Mainly for security reasons, all email server providers limit the maximum email size that an email account can receive. Otherwise, if there would be no maximum email size limit, the email server would risk to be bombarded with very large emails, causing it to cease working properly.
What is the maximum attachment size in Office 365? ›By default, the attachment size limit in Microsoft (Office) 365 is 50 MB. If you need to send a file via email that is larger than 50 MB, you will need to use a different method, such as a listserv or the SendTo application, in order to send the message.
What is the maximum size of attachment in Outlook? ›
Outlook File Size Limit
By default, Outlook does not send email messages with attachments that exceed 20 MB, but many mail servers allow 25 MB or larger attachments. If your email server allows larger attachments, instruct Outlook to send messages larger than 20 MB.
To see the values of these limits, run the corresponding Get- cmdlet for the recipient type in the Exchange Management Shell.
What's the file size limit for Outlook? ›For Internet email account. such as Outlook.com or Gmail, the combined file size limit is 20 megabytes (MB) and for Exchange accounts (business email), the default combined file size limit is 10 MB.
What is the maximum recipient you can add in one email in MS Exchange 2013 2019? ›200 for the Default Frontend, Client Frontend, and Client Proxy Frontend Receive connectors. Note: If the number of recipients is exceeded for an anonymous sender, the message is accepted for the first 200 recipients. Most SMTP messaging servers detect that a recipient limit is in effect.
How do I see the size of an attachment in Outlook? ›In Outlook 2010 and 2013, please click the Size in the Arrangement box on the View tab. In Outlook 2007, please click the View > Arrange By > Size.
How do I start Exchange Powershell? ›On the desktop or the Start screen, press Windows key + Q. In the Search charm, type Exchange Management Shell. When the shortcut appears in the results, you can select it.
How do I fix 552 size limit exceeded? ›Answer: To resolve this error, you will need to adjust the settings on your MTA (Mail Transfer Agent) or Transport Hub. Microsoft Exchange users should see the Microsoft support article Message size limits in Exchange Server for assistance or contact your vendor.
How do I get around 25 MB attachment limit? ›Use Google Drive
If the Gmail email window detects that your attachment is larger than 25MB, the attachment is instead uploaded to your Google Drive account. A link to the file in Drive is then inserted into the email, and the recipient clicks the link and downloads it from Drive.
If the file size is more than 25 MB, you will see “Oops, this email has over 25 MB of files attached. To send these files, please use SkyDrive” message. The best thing is that you can still send your huge file by uploading it SkyDrive. One can upload the file to SkyDrive without leaving Outlook.com.
How do I change the attachment settings in Outlook 365? ›Once Outlook is loaded and you are in your Inbox, click the gear icon in the top-right corner, which is your settings. Click View All Outlook Settings → Attachments. Under Sharing Preferences, you can select from several different options.
What is the maximum number of emails I can send from Office 365? ›
Office 365 users are limited by the following: 10,000 sent email messages per day. 500 recipients total for a single email. 30 emails sent per minute.
How do I increase email size in Outlook 365? ›How to Increase Mail Attachment Size in Office 365 - YouTube