SPF Recors for Additional domains

PaulB 1 Reputation point
2022-05-16T09:00:41.413+00:00

Hi

I have some questions around SPF records.

If we have a domain lets call it main-domain.com and main-domain.com has its own SPF record which includes a mailer and also include:spf.protection.outlook.com -all

If we have a second domain second-domain.com and we want that domain to be able to send email as main-domain.com I assume we would add main-domain.com to the SPF record of second-domain.com using include: main-domain.com

Also where does the include:spf.protection.outlook.com -all come in here? All mail is going out via Online so no on prem. Does include:spf.protection.outlook.com also require adding to the spf record of second-domain.com?

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Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Vasil Michev 94,521 Reputation points MVP
    2022-05-16T10:09:54.547+00:00

    If you add the include clause, it will retroactively add any additional includes. In fact, if you check the spf.protection.outlook.com record, you will see additional includes therein.
    Just be mindful of the 10 lookups limit. There are free "SPF validator" tools online, run the proposed new record against them before making the change, just in case.

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  2. PaulB 1 Reputation point
    2022-05-16T10:32:55.84+00:00

    Hi

    Thanks but that has not really answered my query?

    So adding a domain into the include of an SPF record allows that domain to 'send as' the domain that hosts the SPF record as per my example above if second-domain is added into the SPF record of main-domain than that allows second-domain to send as main-domain?

    Also should spf.protection.outlook.com be added to all domains that send via online exchange?

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