Free tool
Spam Subject-Line Tester
Paste a subject line and we'll flag spam-trigger words, ALL-CAPS, excessive punctuation and length issues that can hurt inbox placement.
How it works
- 1Type your subject line.
- 2We score it against common spam signals.
- 3Rewrite the risky parts before you send.
Questions
Frequently asked
Do subject lines really affect deliverability?
They're one signal among many. Spammy wording, all-caps and excessive punctuation can raise filtering risk, especially combined with a poor list.
What matters more?
List quality and authentication. A clean, verified list and proper SPF/DKIM/DMARC matter far more than any single subject line.
Can I check a whole list at once?
This free tool checks one at a time. To verify a full list — email, phone and company together — upload a CSV to BounceBlock and preview your first 100 rows free.
Stop wasting hours on dead leads.
Upload your list and see how clean it really is — free, in under two minutes.
100 free creditsNo credit cardCancel anytime