How to Set Up SPF Without Breaking Existing Senders
A sequence for adding one sending service to SPF while mail from the tools you already pay for keeps working.
Setting up SPF is the act of editing one TXT record so every legitimate sender is named and the lookup budget still holds. The failure mode is not a missing blog post. It is a record that authorises the new outreach tool and silently stops authorising the helpdesk.
Do it in this order
Export or copy the current TXT. Send a message from each system that uses the domain today and note which ones you cannot afford to break.
- Count mechanisms that cause lookups before you add another include.
- Add the new sender's mechanism to the existing record. Do not publish a second SPF TXT.
- Send from the new tool and from one old system the same hour.
- If the old system fails, remove the new mechanism and ask the vendor for a flatter include or an IP, rather than stacking another lookup.
- Only then point a campaign at the domain.
What Sendblox changes
Once the server Sendblox uses is inside that record, drafting and approval are the remaining work. If SPF fails, no amount of personalisation repairs the authentication result. Keep the DNS change in your own log with the date. Policies and vendor includes change.
Before you publish a change for SPF setup, write down the date, the record you edited, and the one message you used as a test. A week later, check whether that test still matches production. Provider rules, DNS includes, and CRM fields all move. A page that was true in general can be wrong on your domain if nobody looked again. Keep the send small until that check is dull. One contact, one objective, a person reading the draft. If the test fails, stop the campaign. Do not widen it to see whether a larger list forgives a broken setup.
Before you publish a change for SPF setup, write down the date, the record you edited, and the one message you used as a test. A week later, check whether that test still matches production. Provider rules, DNS includes, and CRM fields all move. A page that was true in general can be wrong on your domain if nobody looked again. Keep the send small until that check is dull. One contact, one objective, a person reading the draft. If the test fails, stop the campaign. Do not widen it to see whether a larger list forgives a broken setup.