Features
Diagnostic Tools
Self-service tools to troubleshoot email delivery issues before they affect your reputation
Diagnostic Tools
NorthRelay provides three built-in diagnostic tools to help you identify and resolve delivery issues without contacting support. Access them from Dashboard > Tools.
Pre-Flight Check
The Pre-Flight Check validates your sending configuration before you send a single email. It tests DNS records, SMTP connectivity, and authentication in one pass.
What It Tests
| Check | Description | Pass Criteria |
|---|---|---|
| SPF Record | Verifies your domain has a valid SPF TXT record that includes NorthRelay | Record contains include:_spf.north-pipe.ca |
| DKIM Record | Verifies the DKIM CNAME record points to NorthRelay's signing key | CNAME resolves to the expected NorthRelay target |
| DMARC Record | Checks for a DMARC policy on your domain | _dmarc.yourdomain.com TXT record exists |
| MX Records | Validates your domain's MX configuration (for inbox domains) | MX records resolve correctly |
| SMTP Connectivity | Tests that NorthRelay can establish an SMTP connection for your domain | Connection succeeds within timeout |
| Authentication | Validates your API key and sending permissions | API key is valid and has send permission |
How to Use
- Go to Dashboard > Tools > Pre-Flight Check
- Enter the domain you want to test (must be added to your account)
- Click Run Check
- Review the results -- each check shows pass, fail, or warning with a specific message
Interpreting Results
- All green: Your configuration is correct. You are ready to send.
- Yellow warnings: Non-critical issues (e.g., DMARC policy is
noneinstead ofreject). Sending will work but deliverability may not be optimal. - Red failures: Critical issues that will prevent delivery or cause authentication failures. Fix these before sending.
Each failed check includes an action field explaining exactly what to fix and a link to the relevant documentation.
Blocklist Monitor
The Blocklist Monitor checks your domain and sending IPs against 13 industry-standard DNS-based Real-time Blocklists (RBLs). Being listed on a blocklist can severely impact your deliverability.
Provider Coverage
The monitor checks 13 consolidated providers organized into four tiers by importance:
Tier 1: Industry Standard (3 providers)
These are the blocklists that major mailbox providers actively check. A listing here has the most impact.
| Provider | Type | Description |
|---|---|---|
| Spamhaus ZEN | IP-based | Combined Spamhaus blocklist (SBL + XBL + PBL). The most widely used blocklist. |
| Barracuda | IP-based | Barracuda Networks reputation system. Used by many enterprise mail gateways. |
| SpamCop | IP-based | Crowdsourced spam reporting. Listings are time-based and auto-expire. |
Tier 2: Compromised Hosts & Network Threats (6 providers)
These detect compromised systems, botnets, and network-level abuse.
| Provider | Type | Description |
|---|---|---|
| CBL | IP-based | Composite Blocking List. Detects IPs sending spam from bots/malware. |
| PSBL | IP-based | Passive Spam Block List. Trap-based detection. |
| Invaluement | IP-based | Detects snowshoe spam and bulk senders with poor practices. |
| Backscatterer | IP-based | Detects IPs generating backscatter (bounces to forged senders). |
| 0spam | IP-based | Zero-spam project. Algorithmic detection. |
| SpamRats | IP-based | Detects IPs on dynamic/residential ranges sending spam. |
Tier 3: Reputation & Behavior Systems (3 providers)
These track sending reputation and behavioral patterns over time.
| Provider | Type | Description |
|---|---|---|
| HOSTKARMA | IP-based | Junk Email Filter. Reputation-based scoring. |
| Mailspike | IP-based | Real-time reputation tracking with historical data. |
| SORBS | IP-based | Spam and Open Relay Blocking System. Multiple zone checks. |
Tier 4: Domain & URI Reputation (1 provider)
Checks domain reputation rather than IP addresses.
| Provider | Type | Description |
|---|---|---|
| SURBL Multi | Domain-based | Combined phishing, malware, and abuse domain list. Checks domains in email content. |
How to Use
- Go to Dashboard > Tools > Blocklist Monitor
- Enter a domain or IP address to check
- Click Check
- Results appear grouped by tier in collapsible accordion sections
Result Statuses
| Status | Meaning | Action |
|---|---|---|
| Clean | Not listed on this blocklist | No action needed |
| Listed | Your IP or domain is on this blocklist | Follow the provider's delisting process |
| Warning | Listed on a lower-priority blocklist | Monitor and consider delisting |
| Rate Limited | The blocklist provider rate-limited our query | Try again in a few minutes |
| Offline | The blocklist provider is not responding | Not your issue -- check again later |
| Timeout | Query timed out (3-second limit) | Likely a provider issue -- retry |
| Error | Unexpected error during lookup | Retry; if persistent, contact NorthRelay support |
If You Are Listed
- Identify the cause. Review your Reputation Monitoring dashboard for incidents.
- Fix the underlying issue. High bounce rates and spam complaints are the most common causes of blocklisting.
- Request delisting. Each blocklist provider has a delisting process:
- Spamhaus: https://check.spamhaus.org
- Barracuda: https://www.barracudacentral.org/lookups
- SpamCop: Listings auto-expire after reports stop (typically 24-48 hours)
- Re-check. After delisting, run the Blocklist Monitor again to confirm.
Technical Details
- All 13 providers are queried in parallel
- Each query has a 3-second timeout
- No registration or paid subscription required -- all providers are freely accessible
- Queries use standard DNS-based blocklist lookup (reverse IP + blocklist zone)
Connectivity Doctor
The Connectivity Doctor tests the full SMTP delivery chain from NorthRelay to a destination mail server. Use it to diagnose why emails to a specific domain are failing.
What It Tests
| Check | Description | What It Reveals |
|---|---|---|
| DNS Resolution | Resolves MX records for the destination domain | Whether the destination domain has valid mail servers |
| SMTP Connection | Connects to the destination MX server on port 25 | Whether the mail server is reachable |
| TLS Handshake | Attempts STARTTLS upgrade | Whether the connection can be encrypted |
| EHLO Response | Sends EHLO and checks server capabilities | What extensions the server supports (SIZE, PIPELINING, etc.) |
| Authentication | Tests that NorthRelay's sending IP is accepted | Whether the destination server accepts mail from NorthRelay |
How to Use
- Go to Dashboard > Tools > Connectivity Doctor
- Enter the destination domain you are having trouble delivering to (e.g.,
gmail.com) - Click Test Connection
- Review the step-by-step results
Interpreting Results
Each step shows a pass/fail status with timing information:
- DNS Resolution failed: The destination domain has no MX records or its DNS is misconfigured. This is a problem on the recipient's side.
- SMTP Connection failed: The destination mail server is unreachable. Could be a firewall, server outage, or network issue.
- TLS Handshake failed: The destination server does not support STARTTLS or has a certificate issue. Emails may still deliver without encryption depending on your settings.
- EHLO rejected: The destination server rejected NorthRelay's HELO/EHLO. This could indicate IP-based blocking.
- Authentication rejected: The destination server is rejecting mail from NorthRelay's IP. Check the Blocklist Monitor to see if the IP is listed.
When to Use Each Tool
| Scenario | Recommended Tool |
|---|---|
| Setting up a new domain | Pre-Flight Check |
| Emails going to spam | Blocklist Monitor + Reputation Monitoring |
| Emails not delivering to a specific domain | Connectivity Doctor |
| Routine health check | Blocklist Monitor |
| Investigating a reputation drop | All three tools |
| Before launching a new campaign | Pre-Flight Check |
Related
- Domain Verification for setting up DNS records
- Reputation Monitoring for ongoing sender health
- Sending Infrastructure for how your mail is delivered