SPF records for cold email senders: the complete no-fluff guide
What SPF does, why you need exactly one record, the common errors, and what Inboxlee configures.
Rejwan Nirob·Apr 15, 2026·4 min readSPF (Sender Policy Framework) is a DNS TXT record that lists which servers are allowed to send mail on behalf of your domain. Mailbox providers check it to decide whether to trust an incoming email.
The one-record rule
Your domain may have exactly one SPF record. More than one breaks SPF entirely. If you already have a record for marketing tools, your cold-email provider must be merged in, not appended as a second record.
What Inboxlee sets
On every domain we provision: v=spf1 include:_spf.google.com ~all - the official Google Workspace include with a soft-fail policy. Safe, compatible, and sufficient for Workspace senders.
Frequently asked
What is an SPF record in plain English?
A TXT record published in your domain DNS that lists which mail servers are allowed to send email on behalf of your domain. Gmail and Outlook check this before deciding whether to trust an incoming email - if the sending IP is not in your SPF list, the message is far more likely to land in spam or be rejected.
How many SPF records can a domain have?
Exactly one. The SPF spec forbids multiple TXT records. If you publish two (say, one for Workspace and one for a marketing tool), SPF fails entirely and every email starts from a worse posture. Merge all senders into a single record using includes, like v=spf1 include:_spf.google.com include:sendgrid.net ~all.
What is the difference between ~all and -all in SPF?
~all is a soft-fail policy: tells receivers that mail from unlisted servers should be marked as suspicious but not necessarily rejected. -all is hard-fail: tells receivers to reject outright. ~all is the recommended default for most senders - hard-fail can silently drop legitimate mail if any sender is misconfigured.
Does Inboxlee set up SPF automatically?
Yes. Every domain Inboxlee provisions publishes the official Google Workspace SPF record (v=spf1 include:_spf.google.com ~all) at registration time, before the mailbox is marked live. No manual DNS work required.