TheBRHub Free Tools
Two tools in one. Paste a bounce-back message to decode the SMTP error codes — or enter any domain to check for bounce risk factors before you hit send. Live DNS checks, blacklist spot-checks, and authentication validation — all from your browser.
What We Check
Decode bounce messages after they happen, or predict bounce risk before you send. Both modes run entirely in your browser.
Permanent failures — invalid addresses, dead domains, disabled mailboxes. The decoder categorizes these instantly and tells you exactly which addresses to remove.
Temporary issues — full mailboxes, greylisting, server timeouts. We flag when "temporary" has crossed into "this address is dead" territory based on the specific error pattern.
Content rejections, reputation blocks, and policy violations decoded per provider. Google, Microsoft, and Yahoo each have different triggers — we identify which one you're dealing with.
Microsoft 365 caps at 10,000/tenant/day. Google has per-user limits. These throw errors that look like deliverability failures but are actually throttling — most people misdiagnose this.
Domain risk check queries live MX records, validates the domain resolves, identifies the receiving ESP, and flags misconfigured mail infrastructure before you waste sends on it.
SPF, DMARC, and DKIM selector validation against the target domain. Know if authentication-based rejections are likely before your campaign goes out.
How It Works
Bounce Decoder: Got a bounce notification? Paste it. Domain Risk Check: About to send a campaign? Enter the recipient domain first.
The decoder extracts and categorizes every SMTP code. The risk checker runs live DNS queries against MX, SPF, DMARC, and blacklists — all from your browser.
Every finding comes with specific remediation — which addresses to remove, which DNS records to fix, which blacklists to delist from, and which TheBRHub tools go deeper.
Quick Reference
The codes inside your bounce messages and what they actually mean.
Invalid or deleted address. Hard bounce — remove immediately. Continued sends damage sender reputation.
Blocked by content, reputation, or auth. Google = spam trigger. Microsoft = IP blocklist. Yahoo = reputation.
Recipient over quota. Soft bounce — retry later. If it persists across 3+ sends, treat as inactive.
Sending too fast. Back off, throttle volume. Check M365's 10K/tenant/day and Google's per-user limits.
Failed DMARC alignment + domain has p=reject. Fix SPF/DKIM alignment with From domain.
Malformed email — typos, extra spaces, bad imports. Data quality problem, not a server issue.
Free vs. DeliverCORE
The Bounce Analyzer is always free. For continuous monitoring, automated alerts, and proactive deliverability management — that's DeliverCORE.
Starter plan at $29/mo for up to 5 domains. View all plans →
FAQ
Decode bounce messages after they fail. Check domains before you send. Two modes, one tool, zero cost.