Scan domains and return data based on trustworthy email best practices
trustymail is a tool that evaluates SPF/DMARC records set in a
domain's DNS. It also checks the mail servers listed in a domain's MX
records for STARTTLS support. It saves its results to CSV or JSON.
trustymail requires Python 3.6+. Python 2 is not supported.
trustymail can be installed directly via pip:
pip install trustymail
It can then be run directly:
trustymail [options] example.com
python3 -m trustymail [options] example.com
Using Docker (optional)
opts are the same arguments that would get passed to
Usage and examples
trustymail [options] INPUT trustymail dhs.gov trustymail --output=homeland.csv --debug cisa.gov dhs.gov us-cert.gov usss.gov trustymail agencies.csv
Note: if INPUT ends with
.csv, domains will be read from CSV. CSV
output will always be written to disk, defaulting to
-h --help Show this message. -o --output=OUTFILE Name of output file. (Default results) -t --timeout=TIMEOUT The DNS lookup timeout in seconds. (Default is 5.) --smtp-timeout=TIMEOUT The SMTP connection timeout in seconds. (Default is 5.) --smtp-localhost=HOSTNAME The hostname to use when connecting to SMTP servers. (Default is the FQDN of the host from which trustymail is being run.) --smtp-ports=PORTS A comma-delimited list of ports at which to look for SMTP servers. (Default is '25,465,587'.) --no-smtp-cache Do not cache SMTP results during the run. This may results in slower scans due to testing the same mail servers multiple times. --mx Only check MX records. --starttls Only check MX records and STARTTLS support. (Implies --mx.) --spf Only check SPF records. --dmarc Only check DMARC records. --json Output is in JSON format. (Default is CSV.) --debug Output should include more verbose logging. --dns=HOSTNAMES A comma-delimited list of DNS servers to query against. For example, if you want to use Google's DNS then you would use the value --dns-hostnames='22.214.171.124,126.96.36.199'. By default the DNS configuration of the host OS (/etc/resolv.conf) is used. Note that the host's DNS configuration is not used at all if this option is used. --psl-filename=FILENAME The name of the file where the public suffix list (PSL) cache will be saved. If set to the name of an existing file then that file will be used as the PSL. If not present then the PSL cache will be saved to a file in the current directory called public_suffix_list.dat. --psl-read-only If present, then the public suffix list (PSL) cache will be read but never overwritten. This is useful when running in AWS Lambda, for instance, where the local filesystem is read-only.
For a given domain, MX records, SPF records (TXT), DMARC (TXT, at
_dmarc.<domain>), and support for STARTTLS are checked. Resource records can
also be checked for DNSSEC if the resolver used is DNSSEC-aware.
The following values are returned in
Domain and redirect info
Domain- The domain you're scanning!
Base Domain- The base domain of
Domain. For example, for a Domain of
sub.example.gov, the Base Domain will be
example.gov. Usually this is the second-level domain, but
trustymailwill download and factor in the Public Suffix List when calculating the base domain.
Live- The domain is actually published in the DNS.
MX Record- If an MX record was found that contains at least a single mail server.
MX Record DNSSEC- A boolean value indicating whether or not the DNS record is protected by DNSSEC.
Mail Servers- The list of hosts found in the MX record.
Mail Server Ports Tested- A list of the ports tested for SMTP and STARTTLS support.
Domain Supports SMTP- True if and only if any mail servers specified in a MX record associated with the domain supports SMTP.
Domain Supports SMTP Results- A list of the mail server and port combinations that support SMTP.
Domain Supports STARTTLS- True if and only if all mail servers that support SMTP also support STARTTLS.
Domain Supports STARTTLS Results- A list of the mail server and port combinations that support STARTTLS.
Sender Policy Framework (SPF)
SPF Record- Whether or not a SPF record was found.
SPF Record DNSSEC- A boolean value indicating whether or not the DNS record is protected by DNSSEC.
Valid SPF- Whether the SPF record found is syntactically correct, per RFC 4408.
SPF Results- The textual representation of any SPF record found for the domain.
Domain-based Message Authentication, Reporting, and Conformance (DMARC)
DMARC Record- True/False whether or not a DMARC record was found.
DMARC Record DNSSEC- A boolean value indicating whether or not the DNS record is protected by DNSSEC.
Valid DMARC- Whether the DMARC record found is syntactically correct.
DMARC Results- The DMARC record that was discovered when querying DNS.
DMARC Record on Base Domain,
DMARC Record on Base Domain DNSSEC,
Valid DMARC Record on Base Domain,
DMARC Results on Base Domain- Same definition as above, but returns the result for the Base Domain. This is important in DMARC because if there isn't a DMARC record at the domain, the base domain (or "Organizational Domain", per RFC 7489), is checked and applied.
DMARC Policy- An adjudication, based on any policies found in
DMARC Results on Base Domain, of the relevant DMARC policy that applies.
DMARC Subdomain Policy- An adjudication, based on any policies found in
DMARC Results on Base Domain, of the relevant DMARC subdomain policy that applies.
DMARC Policy Percentage- The percentage of mail that should be subjected to the
DMARC Policyaccording to the
DMARC Aggregate Report URIs- A list of the DMARC aggregate report URIs specified by the domain.
DMARC Forensic Report URIs- A list of the DMARC forensic report URIs specified by the domain.
DMARC Has Aggregate Report URI- A boolean value that indicates if
ruaURIs that tell recipients where to send DMARC aggregate reports.
DMARC Has Forensic Report URI- A boolean value that indicates if
rufURIs that tell recipients where to send DMARC forensic reports.
DMARC Reporting Address Acceptance Error- A boolean value that is True if one or more of the domains listed in the aggregate and forensic report URIs does not indicate that it accepts DMARC reports from the domain being tested.
Syntax Errors- A list of syntax errors that were encountered when analyzing SPF records.
Debug Info- A list of any other warnings or errors encountered, such as DNS failures. These can be helpful when determining how
trustymailreached its conclusions, and are indispensible for bug reports.
We welcome contributions! Please see
This project is in the worldwide public domain.
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