Recipient validation is the process of checking the recipients(s) of an inbound email to one of your internal domains from an external sender. This check is configured at the domain level and there are the following types to choose from:
|Inbound Check Type||Additional Requirements||Description|
|Accept Any Address||None||Mimecast accepts messages for any address in the domain.|
|Send Only Domain||Only Mimecast Support can set a domain to be considered send only. Users with an email address in a send only domain cannot login to Mimecast applications. See the Mimecast Domain Types page for more information.||This option allows your organization to send outbound emails from a domain, but not receive inbound emails to the domain. A send only domain could be used in scenarios requiring the sharing of internal domains, where emails only need to be sent outbound from one of the two accounts.|
|Known Recipients Only|
All users that you want to receive mail from, must be added to Mimecast. The first time a user sends an email outbound via Mimecast, a user is created. Users can also be added to Mimecast individually, using a spreadsheet import, or using Directory Sync.
Mimecast only accepts messages for addresses that display when you open the domain. The list is a combination of addresses that are:
|Known POP Users Only|
All users that you want to receive mail from via POP, must be added to Mimecast.
Limits inbound messages that arrive by POP, to be received by known users listed in the domain.
|Directory Users Only||Directory Sync from your company directory to Mimecast. See the Directory Synchronization page for further details.||Mimecast will only accept messages for addresses within the domain that have been synchronized from your local directory.|
|SMTP Call Forward||Exchange Recipient Filtering must be enabled. See the Enabling Exchange Recipient Filtering for SMTP Call Forward page for further details.||Mimecast contacts your Exchange server using the original "Mail From" address to check if the recipient address is part of the Recipient Filtering list in your Exchange environment. Only messages for addresses that have been verified by your Exchange environment will be accepted by Mimecast.|
|SMTP Call Forward With <>||Exchange Recipient Filtering must be enabled. See the Enabling Exchange Recipient Filtering for SMTP Call Forward page for further details.|
Mimecast checks the original "Mail From" address against your Exchange using a null sender (<>), to ensure the recipient address is part of its Recipient Filtering list. Only messages for addresses that have been verified by your Exchange environment are accepted by Mimecast.
|Act as Backup MX||None||Mimecast only accepts messages for the domain (any address) if your mail server is unavailable. A SMTP Call Forward Route is used to determine availability.|