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Emailing to Groups

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I have set up a number of contact groups in an Office365 email account. For some of the groups, if I try to send an email it returns one of two error messages, one saying that I have reached my quota of emails for the day, the other saying that a problem occurred while trying to use my mailbox. 

Is there a limit on the number of contacts I can put in a Group? Or could there be another cause of this error?

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  • Hello Hardware Frank,

    Yes there are limits on the number of emails you can send per time period, and also on recipients.  The values are available from the "Microsoft Exchange Online for Enterprises Service Description.docx" at  They are also available from "Message and Recipient Limits" at


    If you need to send to a lot of recipients in your O365 company, then I recommend that you setup and use a distribution group as this will keep the count down.


    Message limits

    These limits are applied to every e-mail message.

    Limit Value

    Message size limit   The maximum total size of an e-mail message. The total size includes the message header, the message body, and any file attachments.

    Note   An e-mail client may limit the size of an individual file attachment to a value much less than the message size limit. For example, in Outlook Web App, the maximum individual file attachment size is 10 MB.

    25 MB

    File attachments limit   The maximum number of file attachments allowed in an e-mail 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.

    125 attachments

    Subject length limit   The maximum number of text characters allowed in the subject line of an e-mail message.

    255 characters

    Multipart message limit   The maximum number of message body parts that are allowed in a MIME multipart message.

    250 parts

    Embedded message depth limit   The maximum number of forwarded e-mail messages that are allowed in an e-mail message.

    30 embedded messages


    Recipient and sender limits

    These limits are applied to messages, senders, or recipients to combat spam and mass-mailing worms or viruses.

    Note   For distribution groups stored in the shared address book, the group is counted as one recipient. For distribution groups stored in the Contacts folder of a mailbox, the members of the group are counted individually.

    Limit Value

    Recipient limit   The maximum number of message recipients allowed in the To:, Cc:, and Bcc: fields.

    • Microsoft Live@edu   100 recipients
    • Microsoft Office 365 for enterprises    500 recipients

    Message rate limit   The maximum number of e-mail messages that can be sent from a single e-mail client per minute. The client is identified by the user account.

    • 30 messages per minute

    Recipient rate limit   The maximum number of recipients that can receive e-mail messages sent from a single cloud-based mailbox in a 24 hour period.

    • Microsoft Live@edu   500 recipients per day
    • Office 365 for enterprises    1,500 recipients per day


    Thank you,

    Todd Douglass - MSFT Support Engineer