Mail autoconfiguration
The Mail Autoconfiguration checker verifies that mail clients can automatically discover how to connect to your mail servers. When autoconfiguration is published correctly, a user only types their email address and password, and their client (Thunderbird, Outlook, mobile mail apps…) finds the right IMAP/POP and SMTP hosts, ports and security settings on its own.
This checker is service-level: it applies to the mail-autoconfiguration and RFC 6186 services of a domain. For each run it probes the discovery mechanisms used by real-world clients:
- Thunderbird autoconfig (Bucksch draft):
https://autoconfig.<domain>/mail/config-v1.1.xmlas the primary URL, with thehttps://<domain>/.well-known/autoconfig/...apex fallback, an optional plain-HTTP variant, the Mozilla ISPDB fallback, and MX-parent fallbacks. - Microsoft Autodiscover (POX):
https://autodiscover.<domain>/autodiscover/autodiscover.xml. - RFC 6186 SRV records:
_imaps,_imap,_pop3s,_pop3,_submissions,_submission,_autodiscover. - MX resolution, for context and MX-based discovery.
It parses every response, cross-checks the servers advertised by the different sources, and produces an HTML report with paste-ready remediation snippets for the most common failure modes.
What it checks
| Rule | What it verifies | Severity on failure |
|---|---|---|
autoconfig_presence |
At least one autoconfiguration discovery method answers for the domain. | Critical |
autoconfig_preferred_endpoint |
The primary URL https://autoconfig.<domain>/mail/config-v1.1.xml is reachable and serves a valid clientConfig. |
Warning |
autoconfig_tls |
Autoconfig endpoints are served over HTTPS with a valid TLS certificate. | Critical |
autoconfig_server_encryption |
Servers advertised by autoconfig use SSL or STARTTLS and a non-cleartext authentication method. | Critical |
autoconfig_consistency |
Hostnames and ports reported by autoconfig, Autodiscover and SRV records agree with each other. | Warning |
autoconfig_srv_records |
RFC 6186 SRV records complement the autoconfig XML. | Warning |
autoconfig_autodiscover |
Whether Microsoft Autodiscover (POX) responds on the domain. | Warning |
When a check fails, the report’s “Fix this first” section provides ready-to-copy snippets: a sample config-v1.1.xml and its canonical URLs when nothing is published, a nudge to add the autoconfig. subdomain when only .well-known answers, an HTTPS redirect hint, a certificate-coverage hint, a port cheat-sheet for plaintext servers (SSL 993/465, STARTTLS 143/587), and a ready-to-paste SRV zone excerpt.
Options
Per user
| Option | Meaning | Default |
|---|---|---|
Local-part used in probes (probeEmail) |
Local part sent in the autoconfig URL query string (before @). Most servers ignore it. |
test |
HTTP timeout (httpTimeout) |
Per-request timeout, in seconds, when probing endpoints. | 8 |
Try Mozilla ISPDB fallback (tryISPDB) |
When the domain publishes no autoconfig file, also query Mozilla’s public Thunderbird ISPDB. | true |
Allow plain-HTTP fallback probe (tryHTTPAutoconfig) |
Also probe the plain-HTTP variant of autoconfig.<domain> (optional in the draft); useful to spot HTTP-only providers. |
false |
Probe Microsoft Autodiscover (tryAutodiscoverPost) |
Probe the Exchange/Outlook Autodiscover endpoints. Disable to check only the Thunderbird flow. | true |
Admin
| Option | Meaning | Default |
|---|---|---|
Mozilla ISPDB base URL (ispdbURL) |
Base URL of Mozilla’s autoconfig fallback database. | https://autoconfig.thunderbird.net/v1.1/ |
User-Agent used in probes (userAgent) |
User-Agent announced in every probe request. | happyDomain-autoconfig/1.0 (+https://happydomain.org) |
In happyDomain
Enable this checker from the Checks tab of the relevant mail-autoconfiguration service. See /en/pages/checks/ for scheduling and reading checks.
This checker is the natural companion to a full mail setup: see /en/reference/services/email/ for the MX, SPF, DKIM and DMARC services that govern how mail is delivered and authenticated.