SPF records
If you use sender domains (and you should!), Copernica takes care of creating all your relevant DNS records. You only have to create a couple of aliases in your own DNS that refer to the settings that we created. For most of the records (the tracking domain, DKIM, DMARC) we recommend to use CNAME records for these aliases. For SPF however you should make a TXT record.
A SPF record is a DNS record that holds, simply put, a list of IP address that you use to send out email from. A domain owner can use SPF to publish a list of IP addresses that he uses for email. A receiving party (like gmail.com or live.com) can query this list, and check if incoming emails were indeed sent from an expected IP. If a receiver gets an email that appears to come from you (because it uses your domain), but that was sent from an IP address not on your SPF list, he knows that something strange is going on, and can take action. This does not necessarily mean that your email will be blocked, but it certainly is now a good sign and you therefore better make sure that the list of IPs on your list is up-to-date.
Everybody always speaks (and we write) about SPF records as if an SPF record is a special type of DNS record, just like A, AAAA and MX records. From a technical standpoint this is not completely correct. A SPF record is implemented in DNS as a normal TXT record holding textual content. By putting the text "v=spf1" in front of the value of a TXT record it gets a special meaning and email programs and email receivers recognize it as a record with SPF settings. When we speak about SPF records we therefore actually mean "a TXT record that begins with v=spf1".
And there is a second nuance. We explained that SPF holds a list of IP addresses. This is indeed what the record contains, but it is, if you want to precise, a too simplistic descriptions of the record's contents. A SPF record can indeed hold IP addresses, but it can contain other elements too, like domain names, redirects and includes. If you do a SPF record lookup, you will not only receive a list of IP addresses, but also all these other elements. But this other elements trigger additional (recursive) lookups, until all the elements have finally been brought back to (after all) a list of IP addresses.
Copernica utilizes these additional elements. If you go to the sender domain dashboard in Marketing Suite, you get a list of recommended DSN settings. For most of the records we recommend to use CNAME record, because CNAME is the standard record type for aliases and referals. For SPF however, we recommend to create a regular TXT record holding an "include" element. In practice both a CNAME record and a SPF record with an include do the same thing: your own DNS settings refers to the setting in our DNS.
What should be listed in the SPF record
If you send mail with Copernica, it speaks for themselves that Copernica's IP addresses also have to be included in the SPF record. Receivers can only then validate that the messages that we send on your behalf (and that come from our IP's) are legitimate. But because we create your DNS record we already take care of this and you can sit back and relax (if you correctly set up the alias).
You may already know that email messages use two different sender addresses: the "normal" from address that you normally see when you open a message, and a second address that we call the envelope address. This envelope address is not displayed to the user and is intended for communication between mail servers. When a message bounces (could not be delivered), receiving servers can send back an error to this envelope addresses. We add such an envelope address to the mail that we send on your behalf, so that we can process the bounces on your mailings.
Every mail that we send gets a unique bounce address, using a subdomain of your main domain. If you have created a sender domain for "yourcompany.com", we for example use "feedback.copernica.com" subdomain in the envelope address to collect the bounces. Because SPF was designed to verify these envelope addresses, the recommended SPF setting is also for the subdomain, and not for the main domain.
In normal circumstances you do not have to edit the recommended SPF setting. The standard recommendation refers to a list of IP addresses of the Copernica server, and is normally (always) sufficient because only we use your subdomain to send out mail. However, if, for whatever reason, you want to modify the SPF record, you of course are free to do so. You can copy our recommended SPF records and modify it (for example to add more IP addresses to it). Although that is probably not necessary.