Email Deliverability Tools by Job

What do email deliverability tools actually check?

No tool decides whether your message reaches the inbox. The receiving server decides that. Email deliverability tools only measure the things it looks at, or simulate the result. Those inputs are always the same. Is the message authenticated for your From domain? Is the domain or sending IP on a blocklist? Does the address exist? What reputation has the domain built up? How do recipients react? Each type of tool covers one of these questions. None covers all five, so a cold sender running their own Brevo account and sending domain usually ends up combining two or three tools.

Job	What it checks	Named tools (as listed in current search results)	Where it stops
Authentication and DNS check	Whether your SPF, DKIM and DMARC records exist, are written correctly and align with your From domain	MxToolbox	A valid record doesn't mean every message gets signed. You still have to read the Authentication-Results header of a real sent message
Blocklist monitoring	Whether your sending IP or domain is on public blocklists such as Spamhaus	MxToolbox	Gmail and Outlook mostly filter on their own internal reputation, which no public list shows
Inbox placement test	Where a test message lands across a set of seed mailboxes at the major providers	GlockApps, Validity Everest	Seed mailboxes have no history with you, so they can't show how your real prospects' inboxes treat you
List verification	Whether an address and its mail server accept mail, checked before you send	Kickbox, Bouncer	Catch-all domains accept every address at the check and may still bounce or discard the mail later
Warm-up	Sends mail between participating mailboxes, which open and reply to it, to build sending history	Warmy, MailReach	Warm-up traffic isn't prospect traffic, and it can't make up for bounces from a bad list
Provider reputation data	Domain reputation, spam rate and authentication results as Gmail sees them	Google Postmaster Tools	Only shows data once a domain sends enough mail to Gmail. Low-volume cold domains often see nothing

Which email deliverability tool should I use for which job?

Here are the realistic options for each job, all judged the same way: what each one tests and where it stops. Feature lists change, so check each vendor's documentation before you buy.

• DNS and authentication: MxToolbox looks up a domain's SPF, DKIM and DMARC records and flags errors. One example is an SPF record that goes over the DNS lookup limit set by the SPF standard, often after you add one include too many. To check a DKIM key you need its selector. Brevo publishes its own.
• Blocklists: MxToolbox checks a domain or IP against many public blocklists in one query. Use it when a bounce notice names a blocklist, or when replies suddenly drop.
• Inbox placement: GlockApps and Validity Everest send your message to seed accounts at Gmail, Outlook and other providers and report whether it landed in the inbox, in spam or not at all. Use them to compare a template or sending setup before and after a change.
• List verification: Kickbox and Bouncer check addresses before you upload them, so hard bounces don't count against your domain. Run them on every newly sourced list, not just the first one.
• Warm-up: Warmy and MailReach build sending history on a new mailbox by exchanging mail inside their own network. Use them alongside a slow ramp-up to real prospects, never instead of one.
• Gmail reputation: Google Postmaster Tools is Google's own dashboard for a domain you've verified. It shows the spam rate Gmail measures for your mail, your domain reputation and how often authentication passes.

When to use which: you need the DNS check and list verification before the first send, because both prevent damage that takes a long time to undo. Placement tests are for diagnosis, so run one when you change a template, a domain or a sending path. Postmaster Tools is the only one that shows what a mailbox provider itself sees, so treat it as the reference once you send enough for it to report. Setting up the records is covered step by step in our guide to DKIM, DMARC and SPF for cold email senders.

What can't deliverability tools tell you?

Most wasted effort comes from treating a tool's output as a final verdict. These are the common misreadings and their causes:

• "All records green" but mail still lands in spam: the records are valid, but DKIM is signed by a different domain than your From address, so DMARC alignment fails. Only the headers of a real delivered message show which domain signed it.
• A clean placement test, then poor results: seed inboxes have no engagement history and no complaints from your prospects. Your real recipients' providers look at how those people react to you.
• No blocklist hits, but still filtered: Gmail and Microsoft rely heavily on their own reputation systems, which no public list shows.
• A verified list that still bounces: catch-all servers accept any address during verification and reject or drop the mail later. Treat catch-all results as unverified.
• Warm-up looks healthy, live sends don't: warm-up mail gets opened and answered by design. Prospect mail doesn't, and jumping straight from warm-up volume to full cold volume looks like a new sending pattern.
• An empty Postmaster Tools dashboard: this doesn't mean you're in good standing. It means Gmail hasn't seen enough mail from the domain to report anything.

If a tool shows a problem you can't explain, look at the bounce notices next. Their status codes show which check failed. Our article on email bounce codes and their causes explains how to read them.

In what order should a cold sender use these tools?

1. 1 Publish and check your DNS records: one SPF record that includes Brevo, Brevo's DKIM key, and a DMARC record at _dmarc that starts with p=none. Then confirm all three with a DNS lookup tool.
2. 2 Send one message to a mailbox you control and read its Authentication-Results header. You want spf=pass, dkim=pass with your own domain in d=, and dmarc=pass.
3. 3 Verify the prospect list and remove invalid and catch-all addresses before you import it.
4. 4 Warm up the mailbox and domain gradually, with real sends to verified prospects that increase slowly.
5. 5 Run a placement test whenever you change the template, the domain or the sending path. Compare the result with the previous run rather than with a fixed target.
6. 6 Verify the domain in Google Postmaster Tools and watch the spam rate and domain reputation once data appears.
7. 7 Check blocklists when a bounce notice mentions one or when results change suddenly.

Step four is where most new domains go wrong. Our guide to email warm-up with daily volumes and DNS setup covers the ramp-up. For the reputation signals in steps six and seven, see sender reputation: check, build and fix.

How EmailFlow OS sends video email through your own domain

EmailFlow OS isn't a deliverability tool and doesn't replace any of the tools above. It handles the sending side of personalised video outreach. You record one video and upload it to EmailFlow OS, connect your Brevo account and your sending domain, and import your prospect list into EmailFlow OS. EmailFlow OS then makes a personalised version of that one recording for each recipient (per person, not per company). It sends each version from your own inbox, through your own Brevo account and your own sending domain. No shared platform sender is involved.

This matters for the tools above. Because the mail goes out under your domain, the DKIM signature, the DMARC result and the Postmaster data all belong to you. A placement test or header check measures a setup you control, and the reputation you build stays with your domain if you change tools later. The receiving server still decides where a message lands. What EmailFlow OS changes is whose domain gets judged. Each step is described on the EmailFlow OS features page.

Do sales follow-up emails need their own deliverability checks?

Follow-ups go out from the same domain, so they count toward the same reputation. Each of these common follow-up questions has a deliverability side:

• Sales follow up email template: keep it short, refer to the first message, and send it as a reply in the same thread. A real reply carries In-Reply-To and References headers that point to the original Message-ID. Copying a "Re:" subject line without those headers doesn't put the message in the thread.
• Follow up sales email: a second or third message to someone who didn't answer the first one. It goes out from the same From address and domain, so it passes or fails SPF, DKIM and DMARC exactly like the first message.
• Sales email follow up templates: write separate versions for no reply, after a call, and a final closing message. Drop any address that hard-bounced from the sequence, because each new send to it adds another bounce against your domain.
• Sales follow up email: every follow-up still needs a working unsubscribe link. Google's email sender guidelines ask bulk senders for one-click unsubscribe, and a recipient who can't opt out is more likely to hit the spam button.
• Sales follow up email examples: "Quick follow-up on my note from Tuesday about your onboarding flow. Is that worth a short call, or should I leave it?" works as a reply in the same thread. More copy-ready versions are in our sales follow-up email template examples.

For the full set of templates by situation, see sales follow-up email template examples. EU senders should keep in mind that no reply to a first cold email isn't consent. In Germany, the unfair competition law (UWG) sets the rules for unsolicited advertising email, and sending a follow-up doesn't change them.

Questions people ask

? Are free email deliverability tools enough for cold email?

For setup, often yes. Google Postmaster Tools is free from Google, and you can look up your SPF, DKIM and DMARC records with free lookup tools or dig. Free tiers usually limit repeated seed-list placement tests and bulk list verification. Those are the two jobs that grow with your sending volume.

? What is the difference between an inbox placement test and a delivery rate?

Delivery rate is accepted messages divided by sent messages, so it counts mail in the spam folder as delivered. An inbox placement test sends to seed mailboxes and reports where the message actually landed: inbox, spam or nowhere. A message can count as delivered and still never reach the inbox.

? Does a warm-up tool fix a damaged sender reputation?

No. Warm-up builds sending history on a new or quiet mailbox by exchanging mail that gets opened and answered inside a network. It doesn't remove complaints, bounces or blocklist entries. On a damaged domain, fix the cause first, such as an unverified list or failing DMARC alignment. Then send low, steady volume to real recipients.

? Which header shows whether my email passed SPF, DKIM and DMARC?

The Authentication-Results header, which the receiving server adds. In Gmail, open the message and choose Show original. Look for spf=pass, dkim=pass with your own domain in d=, and dmarc=pass. If d= shows a different domain, DMARC alignment fails even though DKIM passes.