Invalid Internal Recipient

The Invalid Internal Recipient MailTip is displayed if the sender adds a recipient that appears to be internal to the organization but doesn't exist.

This could happen if the sender addresses a message to a user who is no longer with the company but whose address resolves due to name resolution cache or an entry in the sender's Contacts folder. It can also happen if the sender types an SMTP address with a domain for which Exchange is authoritative and the address doesn't resolve to an existing recipient.

The MailTip indicates the invalid recipient and gives the sender the option to remove the recipient from the message.

Mailbox Full

The Mailbox Full MailTip is displayed if the sender adds a recipient whose mailbox is full and your organization has implemented a Prohibit Receive restriction for mailboxes over a specified size.

The MailTip indicates the recipient whose mailbox is full and gives the sender the option to remove the recipient from the message.

The MailTip is accurate at the time of display. If the message isn't immediately sent, the MailTip is updated every two hours. This also applies to messages that were saved in the Drafts folder and reopened after two hours.

Automatic Replies

The Automatic Replies MailTip is displayed if the sender adds a recipient who has turned on Automatic Replies.

The MailTip indicates the recipient has Automatic Replies turned on and also displays the first 250 characters of the automatic reply configured by the recipient.

The MailTip is accurate at the time of display. If the message isn't immediately sent, the MailTip is updated every two hours. This also applies to messages that were saved in the Drafts folder and reopened after two hours.

If part of your user mailboxes are hosted on Exchange Online and you're in a coexistence with Exchange Online scenario, the setting on the remote domain object that represents the remote part of your organization has a direct effect on how this MailTip is processed.

In Exchange 2013, users can configure different Automatic Replies for internal and external senders. If the remote domain is configured as an internal domain (by setting the IsInternal parameter on the remote domain object to $true), the internal automatic reply is returned to all users in the organization regardless of where their mailbox resides. However, if the remote domain isn't configured as an internal domain, the internal automatic reply is returned to all users whose mailboxes are in the local domain and the external automatic reply is returned to users whose mailboxes are in the remote domain.

Custom

A custom MailTip is displayed if the sender adds a recipient for whom a customized MailTip is configured.

A custom MailTip can be useful for providing specific information about a recipient. For example, you can create a custom MailTip for a distribution group explaining its purpose to reduce its misuse. For more information, see Configure Custom MailTips for Recipients.

By default, custom MailTips aren't displayed if the sender isn't allowed to send to that recipient. In that case, the Restricted Recipient MailTip is displayed. However, you can change this configuration and have the custom MailTip also display.

Restricted Recipient

The Restricted Recipient MailTip is displayed if the sender adds a recipient for which delivery restrictions are configured prohibiting this sender from sending messages.

The MailTip indicates the recipient to which the sender isn't allowed to send messages and gives the sender the option to remove the recipient from the message. It also clearly informs the sender that the message won't be delivered if sent.

If the restricted recipient is an external recipient, or if it's a distribution group that contains external recipients, this information is also provided to the sender. However, the following MailTips, if applicable, are suppressed:

• Automatic Replies
  
  
• Mailbox Full
  
  
• Custom MailTip
  
  
• Moderated Recipient
  
  
• Oversize Message
  
  

External Recipients

The External Recipients MailTip is displayed if the sender adds a recipient that's external, or adds a distribution group that contains external recipients.

This MailTip informs senders if a message they're composing will leave the organization, helping them make the correct decisions about wording, tone, and content.

By default, this MailTip is turned off. You can turn it on using the Set-OrganizationConfig cmdlet. For details, see MailTips Over Organization Relationships.

If part of your user mailboxes are hosted on Exchange Online and you're in coexistence with an Exchange Online scenario, the setting on the remote domain object that represents the remote part of your organization has a direct effect on how this MailTip is processed.

If the remote domain is configured as an internal domain (by setting the IsInternal parameter on the remote domain object to $true), any recipients in this remote domain will be treated as internal and therefore the External Recipients MailTip won't be displayed. However, if the remote domain isn't configured as an internal domain, the recipients in that domain will be considered external and this MailTip will be displayed when a message is being composed to those recipients.

Note:
This MailTip isn't evaluated when composing a message to a distribution group in the remote domain.

Large Audience

The Large Audience MailTip is displayed if the sender adds a distribution group that has more than the large audience size configured in your organization. By default, Exchange displays this MailTip for messages to distribution groups that have more than 25 members. For details, see Configure the Large Audience Size for Your Organization.

The size of distribution groups isn't calculated each time. Instead, the distribution group information is read from the group metrics data.

Moderated Recipient

The Moderated Recipient MailTip is displayed if the sender adds a recipient that's moderated.

The MailTip indicates which recipient is moderated and informs the sender that this may result in delay of the delivery.

If the sender is also the moderator, this MailTip isn't displayed. It's also not displayed if the sender has been explicitly allowed to send messages to the recipient (by adding the sender's name to the Accept Messages Only From list for the recipient).

Reply-All on Bcc

The Reply-All on Bcc MailTip is displayed if the sender receives a Bcc copy of a message and selects Reply to All.

When a user selects Reply to All to such a message, the fact that the user received a Bcc of that message is revealed to the rest of the audience to which the message was sent. In almost all cases, this is an undesirable situation, and this MailTip informs the user of this condition.

Note:
This MailTip is only supported in Outlook Web App.

Oversize Message

The Oversize Message MailTip is displayed if the message the sender is composing is larger than configured message size limits in your organization.

The MailTip is displayed if the message size violates one of the following size restrictions:

• Maximum send size setting on the sender's mailbox
  
  
• Maximum receive size setting on the recipient's mailbox
  
  
• Maximum message size restriction for the organization
  
  

Note:
Due to the complexity of the implementation, the message size limits on the connectors in your organization aren't taken into account.

Note:
This MailTip isn't displayed in Outlook Web App.