Validate your entire mail stack — safely, thoroughly, and automatically.
Comprehensive
Full-stack mail diagnostics from DNS to TLS.
Secure
No mail modified unless explicitly allowed.
Automatable
CI-ready with quiet mode and JSON output.
Deterministic
Clear results. No hidden behavior.
Run it as a stand-alone Bash tool or as a minimal Docker container.
Connectivity
SMTP (25, 465, 587)
IMAPS (993)
ManageSieve (4190)
TLS & security
Certificate validation
Expiry checks
TLS downgrade protection
Cipher & protocol tests
DNS diagnostics
MX
SPF
DKIM
DMARC
BIMI
MTA-STS
TLS-RPT
Authentication
SMTP AUTH (LOGIN)
IMAP LOGIN
Sieve AUTH
Deliverability
RBL blacklist checks
PTR validation
SMTP feature discovery
Environment Variables
All configuration is driven by OCTOMAILTEST_*
OCTOMAILTEST_DOMAIN=email.com
OCTOMAILTEST_HOST=mx1.email.host
OCTOMAILTEST_EMAIL=This email address is being protected from spambots. You need JavaScript enabled to view it.
OCTOMAILTEST_PASS=secret
OCTOMAILTEST_IMAP_PORT=993
OCTOMAILTEST_SMTP_PORT=587
OCTOMAILTEST_SIEVE_PORT=4190
You may also place these in .octomailtest.
Docker Usage
Run everything (default)
docker run --rm \
-e OCTOMAILTEST_DOMAIN=email.com \
-e OCTOMAILTEST_HOST=mx1.email.host \
-e OCTOMAILTEST_EMAIL=This email address is being protected from spambots. You need JavaScript enabled to view it. \
-e OCTOMAILTEST_PASS=secret \
octoleo/octomailtest
Mail only
docker run octoleo/octomailtest mail
IMAP only
docker run octoleo/octomailtest imap
CI / Quiet mode
Suppress banners and separators:
docker run octoleo/octomailtest --ci
Useful for pipelines and logs.
JSON output
docker run octoleo/octomailtest --json
Output:
{
"action": "both",
"output": "..."
}
Perfect for GitHub Actions, monitoring, or ingestion.
Logging to file
docker run \
-e OCTOMAILTEST_LOG=/logs/out.log \
-v $(pwd)/logs:/logs \
octoleo/octomailtest
Logs always go to stdout; file logging is additive.
Stand-Alone Mode (No Docker)
Requirements:
bash
openssl
dig
nc
swaks
coreutils
./mail
./imap
Configuration precedence:
CLI flags
Environment variables
.octomailtest
Defaults
Expose What Others Miss
OctoMailTest provides a deep, reliable diagnostic suite for validating your entire mail infrastructure — from DNS records to TLS handshakes and authentication layers.
We removed the uncertainty from mail troubleshooting. While your infrastructure remains fully under your control, OctoMailTest performs the heavy lifting — systematically testing, validating, and reporting what truly matters.
OctoMailTest was built with infrastructure longevity in mind. Mail systems are complex and evolve constantly - new standards, stricter TLS enforcement, changing authentication requirements, and increasing deliverability scrutiny. As our own infrastructure grows, so do the tools we rely on. OctoMailTest continues to evolve because we depend on it ourselves for validation, monitoring, and continuous improvement.
