Microsoft Office 365 Message limits
The following limits are applied to every email message.
Message size limit Message size limits are necessary to prevent large messages from blocking delivery of other messages and affecting service performance for all users. These limits include attachments, and apply organization-wide to all messages (inbound, outbound, and internal). Messages larger than this limit will not be delivered, and the sender will receive a non-delivery report (NDR). While message size limits can be configured up, down, or on a per-user basis, administrators can also create transport rules to limit the maximum size of any individual attachment. To learn more, see Office 365 now supports larger email messages.
Note: Particular email clients may have lower message size limits or may limit the size of an individual file attachment to a value that is less than the Exchange Online message size limit. Subject length limit The maximum number of text characters allowed in the subject line of an email message.
File attachments limit The maximum number of file attachments allowed in an email message. Even if the total size of all the file attachments doesn't violate the message size limit, there is still a limit on how many attachments are allowed in the message. This limit is controlled by the multipart message limit.
File attachment size limit The maximum file size of a single attachment.
Note: This is the maximum file size of a single attachment. Individual client programs, including Outlook Web App, may limit the size of attachments below this maximum. Exchange ActiveSync does not implement attachment size limits on an individual attachment basis. The total size of all attachments to an Exchange ActiveSync message must be less than the message size limit. Multipart message limit The maximum number of message body parts that are allowed in a MIME multipart message. This limit also controls the maximum number of file attachments that are allowed in a message.
Embedded message depth limit The maximum number of forwarded email messages that are allowed in an email message.
Note:Feature | Office 365 Business Essentials | Office 365 Business Premium | Office 365 Enterprise E1 | Office 365 Enterprise E3 | Office 365 Enterprise E5 | Office 365 Enterprise F1 |
Message size limit - Outlook | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 |
Message size limit - OWA | 112 MB1, 3 | 112 MB1, 3 | 112 MB1, 3 | 112 MB1, 3 | 112 MB1, 3 | 112 MB1, 3 |
Message size limit - Outlook for Mac | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 | 150 MB1, 2 |
Message size limit - migration | 150 MB 4 | 150 MB 4 | 150 MB 4 | 150 MB 4 | 150 MB 4 | 150 MB 4 |
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption with new capabilities)5 | 150 MB | 150 MB | 150 MB | 150 MB | 150 MB | 150 MB |
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption legacy version)5 | 25 MB | 25 MB | 25 MB | 25 MB | 25 MB | 25 MB |
Subject length limit | 255 characters | 255 characters | 255 characters | 255 characters | 255 characters | 255 characters |
File attachments limit | 250 attachments | 250 attachments | 250 attachments | 250 attachments | 250 attachments | 250 attachments |
File attachment size limit - Outlook | 150 MB | 150 MB | 150 MB | 150 MB | 150 MB | 150 MB |
File attachment size limit - OWA 6 | 35 MB | 35 MB | 35 MB | 35 MB | 35 MB | 35 MB |
File attachment size limit - Outlook for Mac | 150 MB | 150 MB | 150 MB | 150 MB | 150 MB | 150 MB |
Multipart message limit | 250 parts | 250 parts | 250 parts | 250 parts | 250 parts | 250 parts |
Embedded message depth limit | 30 embedded messages | 30 embedded messages | 30 embedded messages | 30 embedded messages | 30 embedded messages | 30 embedded messages |
| Note: |
|---|
1 The default maximum message size for Office 365 mailboxes is 25 MB. Office 365 Administrators can specify a custom limit between 1 MB and 150 MB. However, the size of message you can send or receive also depends on what your email client or solution supports. For more information about customizing the maximum allowed message size for your organization, see Office 365 now supports larger email messages. 2 You can send and receive up to 150 MB messages between Office 365 users (where the message never leaves the Office 365 datacenters). Messages that are routed outside of the Office 365 datacenters are subject to an additional 33% translation encoding increase, in which case the maximum message size is 112 MB. 3 OWA accounts for the possibility that your message may be subject to the 33% encoding increase and restricts the size of message you can send to 25% less than the configured setting. For example, if you customize your settings for a 100 MB maximum message size, you can send messages no larger than 75 MB. 4 The size of messages to be moved into Exchange Online are computed by Exchange Online. Versions of Exchange prior to Exchange Server 2013 may report a smaller item size. This limit applies to move based migrations using any supported Exchange Mailbox Replication Service. Other migration methods (Cutover, Staged, IMAP, PST) and other third party tools are limited by the general message size limit. 5 For information about OME with new capabilities, see Set up new Office 365 Message Encryption capabilities built on top of Azure Information Protection. 6 You cannot attach a single file that exceeds 35 MB. Additionally, you cannot attach files that collectively exceed 35MB. For example, if you attach one 34MB file, you can only attach an additional 1 MB file. |
Feature | Exchange Server 2013 | Exchange Online Plan 1 | Exchange Online Plan 2 | Exchange Online Kiosk |
Message size limit - Outlook | 10 MB4 | 150 MB1, 2 | 150 MB1, 2 | 150 MB2 |
Message size limit - OWA | 10 MB4 | 112 MB1, 3 | 112 MB1, 3 | 150 MB1, 2 |
Message size limit - Outlook for Mac | 10 MB4 | 150 MB | 150 MB | |
Message size limit - migration | Not applicable | 150 MB 5 | 150 MB 5 | 150 MB 5 |
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption with new capabilities)6 | 150 MB | 150 MB | 150 MB | 150 MB |
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption legacy version)6 | 25 MB | 25 MB | 25 MB | 25 MB |
Subject length limit | 255 characters | 255 characters | 255 characters | 255 characters |
File attachments limit | 1024 attachments4 | 250 attachments | 250 attachments | 250 attachments |
File attachment size limit - Outlook | 35 MB4 | 150 MB | 150 MB | 150 MB |
File attachment size limit - OWA | 35 MB4 | 35 MB | 35 MB | 35 MB |
File attachment size limit - Outlook for Mac | 35 MB4 | 150 MB | 150 MB | 35 MB |
Multipart message limit | 250 parts | 250 parts | 250 parts | 250 parts |
Embedded message depth limit | 30 embedded messages | 30 embedded messages | 30 embedded messages | 30 embedded messages |
| Note: |
|---|
1 Office 365 Administrators can specify a custom limit between 1 MB and 150 MB. However, the size of message you can send or receive also depends on what your email client or solution supports. For more information about customizing the maximum allowed message size for your organization, see Office 365 now supports larger email messages. 2 You can send and receive up to 150 MB messages between Office 365 users (where the message never leaves the Office 365 datacenters). Messages that are routed outside of the Office 365 datacenters are subject to an additional 33% translation encoding increase, in which case the maximum message size is 112 MB. 3 OWA accounts for the possibility that your message may be subject to the 33% encoding increase and restricts the size of message you can send to 25% less than the configured setting. For example, if you customize your settings for a 100 MB maximum message size, you can send messages no larger than 75 MB. 4 This is the default limit for Exchange Server 2013 organizations. Administrators can change this value for their organization. 5 The size of messages to be moved into Exchange Online are computed by Exchange Online. Versions of Exchange prior to Exchange Server 2013 may report a smaller item size. 6 For information about OME with new capabilities, see Set up new Office 365 Message Encryption capabilities built on top of Azure Information Protection. |
Related Articles
Microsoft Office 365 Mailbox storage limits
Microsoft Office 365 Exchange Online limits More Info Mailbox storage limits The amount of mailbox storage available is determined by the mailbox type and the user’s subscription license. Administrators can reduce maximum mailbox sizes per user or ...Microsoft Office 365 Email Receiving and sending limits
Receiving and sending limits More Info Receiving and sending limits are applied to combat spam and mass-mailing worms or viruses. These limits help to protect the health of our systems and keep our users safe. Receiving limits Receiving limits apply ...Office 365 Unpkey
1. Remove Office 365 license for Subscription based installs (not Shared Computer Licensing scenarios): To remove the Office 365 license, you must run two cscript command lines. The command lines are: A. Run C:\program files <x86>\Microsoft ...Third party Smtp setting in office 365
Configure a connector to send mail using Office 365 SMTP relay More Info This option is more difficult to implement than the others. Only choose this option when: SMTP client submission (Option 1) is not compatible with your business needs or with ...Office Uninstall from a PC for Office 365 products
Uninstall Office from a PC More Info The following steps describe how to uninstall Office products on a PC (laptop, desktop, or 2-in-1). To uninstall Office 2011 or 2016 for Mac, see Uninstall Office 2016 for Mac or Uninstall Office 2011 for Mac. ...