See what actually lands in the inbox.
Before your campaign, outsend opens an SMTP conversation server by server, sends a test message to your seed inbox, and shows you exactly where your email lands: inbox, promotions, or spam. Plus a full SPF/DKIM/DMARC analysis of your sending domain. Free in alpha.
You've built your email list — through scraping, business directory exports, or an email finder. Your campaign is ready to go. But before hitting "send," one simple question should give you pause: how many of those emails will actually land in the recipient's inbox, and how many will end up in spam, bounce, or silently disappear into a promotions folder?
The deliverability verification feature in outsend.xyz covers this critical step. It combines SMTP verification of each address, a real inbox test using seed mailboxes at major providers (Gmail, Outlook, Yahoo, and a few others), and an analysis of your sending domain's SPF/DKIM/DMARC configuration. You launch your campaign knowing your expected delivery rate — not flying blind.
Three levels of verification
Each level addresses a different cause of lost email — dead address, domain reputation, or broken DNS configuration. All three run automatically in sequence.
SMTP Verification
Server-to-server conversation, without sending a real message. The server responds positively (the address exists), negatively (the address doesn't exist), or ambiguously (catch-all). You remove dead addresses before they tank your reputation with bounces.
← 250 OK
→ rcpt to: j@parti.fr
← 550 user unknown
Real Inbox Test
For validated addresses belonging to a major provider (Gmail, Outlook365, Yahoo, and other common providers), a test message is sent from your sending domain to a seed inbox you configure. The tool observes where it lands: inbox, promotions, or spam.
[outlook] → promotions
[yahoo] → spam folder
SPF / DKIM / DMARC
DNS analysis of your sending domain. SPF authorizes servers to send on your behalf, DKIM cryptographically signs each message, and DMARC tells receiving servers what to do when something fails. Without all three records properly configured, Gmail and Outlook will classify a significant share of your messages as spam.
DKIM: 2048-bit selector ok
DMARC: p=none (should be tightened)
Sample DNS report
mydomain.comTXT record found · soft-fail recommended when relaying via Brevo.
Selector brevo._domainkey published · 2048-bit key.
Policy p=none · tighten to quarantine once your SPF/DKIM cohort is stable.
Before/after verification
Three typical scenarios where verification protects both the sender and domain reputation.
500-contact outreach campaign
List extracted by geo-industry area. Without verification → 20% silently trashed.
200 cold job applications
Email finder patterns. Without verification → 30-40 bounces that damage the reputation of the other 160.
SaaS product onboarding launch
DNS audit before first send. Missing SPF → 40% of onboarding messages land in Gmail spam.
The market: credit-based pricing, real inbox testing costs extra
| Tool | SMTP Verification | Real inbox test | Model |
|---|---|---|---|
| NeverBounce | ✓ | × | $0.004/email |
| ZeroBounce | ✓ | paid add-on | $15/mo + credits |
| GlockApps | × | ✓ | $59/mo |
| Mail-Tester | × | partial (score) | 3 free tests / month |
| outsend | ✓ | ✓ built-in | Free in alpha |
What this feature does not do
- No 100% spam-free guarantee — Gmail changes its rules regularly, no tool can guarantee inbox placement indefinitely
- No content audit (spam trigger words, image-to-text ratio) — use Mail-Tester alongside for a broader score
- No campaign sending itself — deliverability audits, while the outsend pipeline send step actually sends
- No automatic DNS repair — the tool tells you what's missing; you publish the records in your DNS host
Test your deliverability for free
SMTP verification + real inbox test + DNS analysis. All inside the outsend pipeline. Free alpha, apply to join — no credit card required.
Request free alpha access →Frequently asked questions
What's the difference between SMTP verification and a real inbox test?
SMTP verification confirms that the address exists (the server accepts it). A real inbox test sends an actual message to a seed inbox you configure and observes whether it lands in the primary inbox, promotions, or spam — so it measures the reputation of your sending domain, not just whether the recipient address is valid.
How many addresses can be verified via SMTP?
In alpha, there is no fixed address cap. The tool manages the pace on the receiving server side to avoid getting blacklisted mid-run. For a list of 500 addresses, expect 10–15 minutes for level 1 verification.
Do I need to provide my own sending domain?
Yes, for the level 2 real inbox test — the tool sends from your domain to a seed inbox you configure. That's what makes the test representative of your actual reputation. For level 1 SMTP verification and level 3 DNS analysis, your domain is enough; no seed inbox is needed.
SPF, DKIM, DMARC — what exactly are they?
Three DNS records published on your domain. SPF authorizes specific servers to send on your behalf (all others are rejected). DKIM cryptographically signs each message to prove it genuinely came from you. DMARC tells receiving servers what to do if a message fails SPF/DKIM (reject, quarantine, or ignore). Without all three, Gmail and Outlook have been classifying a large share of messages as spam by default since 2024.
Why do my emails land in Gmail's "Promotions" tab?
Gmail automatically classifies messages that look like newsletters (List-Unsubscribe header present, image-heavy, marketing content detected) into Promotions. For one-to-one outreach, a conversational tone + clean signature + no images helps land in Primary. The outsend inbox test shows you which tab you end up in.
Does this feature replace Mail-Tester?
Partially. Mail-Tester also analyzes content (spam trigger words, image-to-text ratio). outsend focuses on address verification + real inbox test + DNS. The two tools are complementary: Mail-Tester before finalizing your copy, outsend before each campaign to validate the list and the domain.