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What are the limitations of my hosted Exchange account?

Limitations on several items may be applied according to your Exchange hosting plan. Some of these limitations are configurable. If you would like to configure some of these limitations, please open a support ticket at http://www.shieldinformation.com/help

Incoming and outgoing message size
  • Mailboxes are set up by default with the maximum message size limit of 51200 KB (50 MB) for both sending and receiving messages. This limit can be decreased, if desired.
  • Mailbox-specific limits are not respected by EWS mail clients, such as Entourage EWS, Outlook 2011 or Apple Mail Exchange account.
  • The message size limit for the emails sent from Activesync devices is 20 MB in total and ~16.6 MB for attachments. Due to the routing the size of a message increases by about 20% which means that the original size of a message sent from a mobile device should be less than 16 MB.
  • Due to message encoding that is used to transfer the message through the Internet, the size of the message can grow substantially. The "encoded message size" is the size of the resulting email message with all of the attachments added and encoded using MIME. This encoded size is the actual size of the message as it travels over the Internet and is always larger than the raw size because of the MIME overhead and because binary attachments are generally encoded using base64 encoding. Base64-encoded files are usually about 137% the size of the original files. Additionally, the encoded message contains all of the metadata about the message — and this information grows as the message travels from the sender to the recipient.
  • WARNING: If you send a very large message, it stays in the Outbox until the file is uploaded to the server. This can block other messages. Please keep this in mind regarding message size limits.

Recipients per message (number allowed per message)
  • The maximum number of recipients per message depends on the plan selected for your account. By default this setting is set to maximum for each user on the account. You may set this limit to a lower number, if desired.
  • On hosted Exchange, if the message is sent to a distribution list created on your hosted Exchange account, the distribution list is viewed as one (1) recipient regardless of the number of members in the list. If the contact group (sometimes called local distribution list) is created in OWA, the number or recipients is equal to the number of members.

Mailbox size
  • By default mailbox size is not limited. 
  • The size limitation is set for the whole account storage which depends on your plan. To check the current usage and add additional storage, please open a support ticket at http://www.shieldinformation.com/help
  • However, we do not recommend to maintain large mailboxes as it can lead to poor Outlook performance. While the overall size of .ost files has a preconfigured limit of 50 gigabytes (GB), Microsoft recommends to avoid the Outlook data files growing larger than 10 GB. Read the Microsoft KB article on the connection between Outlook data file size and Outlook behavior for more information.
  • You can control the size of individual mailboxes by establishing send and receive limits for the mailboxes in your account. To configure limits for individual mailboxes, please open a support ticket at http://www.shieldinformation.com/help

Other limitations
  • Company Contacts (total number allowed)
  • Distribution lists (total number allowed)
  • Inbound domains (total number allowed)
  • Maximum attachment size per email (KB)
  • Top-level public folders (total number allowed)
  • Maximum public folder item size (MB)
  • Note: if you're using an SMTP application to send messages via an authenticated relay, there is a limitation of 50 messages per minute per connector.
Creation date: 5/12/2020 7:03 PM (lee@shieldinformation.com)      Updated: 5/12/2020 7:03 PM ()
Information about account management for hosted Exchange accounts