Move to iBlockSpam: our guided cutover plan

The short answer

To switch filters safely: lower your MX TTL a day or two ahead, save a copy of your current DNS, configure your mail platform to accept mail from the new filter before touching MX, change MX, test, and keep the old filter active until the old TTL has passed. Keep rollback steps ready the whole time.

This page is the plan we guide iBlockSpam customers through. For the vendor-neutral background, read our guides on switching spam filter providers and changing MX records without losing email.

Why migrations lose mail

Mail is rarely lost because of the new filter itself. It's lost in the gaps:

• The mail platform rejects mail from the new filter because it wasn't told to expect it.
• The old filter is canceled while some senders still use cached MX records.
• Inbound restrictions are tightened before delivery is verified.
• Nobody wrote down the old records, so rollback is guesswork.

Each step below closes one of those gaps.

Step by step

1. Check where you are (day −3 or earlier)

Run the Email Health Check and MX Lookup. Note your current MX hosts, SPF and DMARC. An MX lookup shows where mail is routed; it can't prove mail is filtered, so also check a recent message's headers with the Email Header Analyzer.

2. Snapshot your DNS

Save your current MX records (host, priority, TTL), SPF and DMARC records as text. Our guided setup wizard records this snapshot and shows a before/after comparison later.

3. Lower the TTL (24–48 hours ahead)

Reduce the TTL on your MX records, for example to 300 seconds. Then wait at least as long as the old TTL, because resolvers keep the old value until it expires. A low TTL makes both the cutover and any rollback take effect faster.

4. Stage the destination before changing MX

Set up your mail platform to accept mail from the new filter while it's still receiving from the old one.

Don't yet restrict delivery to the new filter only. That comes after verification.

5. Cut over MX

Replace the old MX records with the values shown in your iBlockSpam setup. Remove the old filter's MX entries rather than leaving them at a lower priority; a leftover backup MX lets mail bypass filtering.

6. Test and verify

• Send messages from an outside account (a personal mailbox works) to a mailbox you own.
• Confirm arrival, then check headers to see that mail passed through the new filter.
• Check that the message appears in your iBlockSpam message history.
• Ask a few colleagues to confirm normal mail is arriving.

7. Watch both paths during propagation

For the length of the old TTL (and a little longer), some senders will still deliver via the old filter. Keep it active and delivering. Watch its logs as traffic tails off.

8. Tighten and tidy up

Once delivery is verified and the old filter shows no new traffic:

• Consider restricting inbound delivery to the new filter's connector or gateway.
• Update SPF if the old service sent mail for you and no longer will.
• Raise the MX TTL back to a normal value.
• Cancel the old filtering service.

Domain monitoring will then alert you if MX, SPF or DMARC drift (weekly on Protect, daily on Protect Plus).

Rollback plan

Write this down before cutover:

1. Restore the saved MX records at your DNS provider.
2. Revert any platform restriction that only accepts mail from the new filter.
3. Make sure the old filter is still active and expecting your domain.
4. Send a test message and confirm arrival.

If your mail server itself is unavailable during the change, iBlockSpam holds inbound mail for up to 5 days and delivers it when the server is reachable again.

Need a hand?

Protect Plus includes a human setup session. On either plan, contact us before you start if your setup includes split delivery, secondary MX, catch-all addresses or an on-premises server. Our support page explains what to include so we can help quickly.