Understand the two results

In an SPF mechanism, ~ produces softfail when that mechanism matches; - produces fail. The common endings ~all and -all therefore classify connections that reached the end without matching an earlier authorized source.

Softfail is a weak statement that the host is probably not authorized. Fail is an explicit statement that it is not authorized. Neither result requires every receiver to place or reject a message in one universal way. Receivers combine SPF with local policy and other evidence. SPF also evaluates an SMTP identity, not the visible From address by itself.

Inspect what would be affected

Before changing the qualifier, enumerate current legitimate sending IPs and services for the exact MailFrom domain. Trace includes and check for processing errors. Review recent trusted receiver evidence and authorized authentication reports. Unknown sources need an owner and disposition; a source is not legitimate merely because it appears in logs.

Build a change table:

Source Current result Expected after change Owner Evidence
Provider A pass pass Product mail Fresh received test
Retired host softfail fail None Decommission record
Unknown IP softfail fail Investigate No approval yet

Check the broader authentication path

If DMARC relies on SPF for some streams, confirm that the passing SPF domain aligns with the visible From domain. Verify DKIM independently. Forwarding can change the connecting IP and cause SPF to fail even when the original sender was authorized, so inspect indirect paths rather than promising that -all will be harmless everywhere.

Make a reversible change

Record the current policy, new policy, TTL, approval, expected receiver observations, monitoring window, and rollback trigger. Publish only after every legitimate source has a tested path. Query authoritative and recursive DNS, then send a fresh message from each stream.

Monitor SPF results, bounces, and DMARC outcomes by source. Roll back if legitimate traffic changes unexpectedly and investigate the inventory gap. The right qualifier is the one that truthfully represents your authorization and is supported by operations—not the one described as “strict” in a generic scorecard.