Understanding SPF Records
SPF records give mail servers permission to send mail on behalf of a domain. They can be designated as SPF or TXT records on the nameserver.
Hostname: @ OR [ma]
Value: v=spf1 a mx ip4:[ip address] ~all
Understanding DKIM
DKIM is a TXT record.
Obtain the record from the mail server. It looks like:
Hostname: [mailo.]_domainkey.[mg]
Value: k=[rsa]; p=[y6t7tfygjkbkhygu7t8…]
DMARC
DMARC is a TXT record.
Hostname: _dmarc.[mg]
Value: v=DMARC1; p=none;
Tests
- Mail-Tester – Newsletters spam test
- Limited tests per day by IP address
- Comprehensive
- MailGenius – Free Email Tester – Email Spam Checker – Email Deliverability Tester
- Comprehensive
- Unlimited
- UnSpam – Email Tester, Spam Checker Reputation and Deliverability
- Possibly not accurate
- Comprehensive reporting
- Unlimited
- MxToolBox – Email Deliverability Tool – Check Your Deliverability Report
- Comprehensive
- Unlimited
- GlockApps – Your expert on email deliverability
- Register to use
- SendForensics
- Register to use
- https://www.senderscore.org/get-your-score/
- Register to use
- Mailtrap.io — Fake smtp testing server. Dummy smtp email testing
- Register to use
- TheChecker: Email Checker & Email Verifier Service
- Register to use
- Email Verifier- Bulk Email Validation Service | MEV
- Register to use
- NeverBounce: Bulk Email Verification & List Cleaning Service
- Register to use
Services
Checklists
DKIM
Validate: DKIM Validator tool
Understanding Errors:
SPF
Create an SPF record:
Test:
- SPF record Checker | SPF record Tester – Mimecast
- SparkPost SPF Inspector
- Kitterman
- dmarcian
- Dig Web Interface
BIMI
Create a record:
Spam
Test:
DMARC
To pass DMARC authentication, a message must both Pass and Align for either SPF or DKIM. Even if a message passed authentication for both SPF and DKIM, it could still fail DMARC authentication if one of them does not “align.”
Record Generator:
Setup Guides
Test:
DMARC Tags
| tag | explanation |
| v | DMARC protocol version. |
| p | Apply this policy to email that fails the DMARC check. Can be “none”, “quarantine”, or “reject”. “none” is used to collect the DMARC report and gain insight into the current email flows and their status. |
| rua | A list of URIs for ISPs to send XML feedback to. NOTE: this is not a list of email addresses. DMARC requires a list of URIs of the form “mailto:test@example.com”. |
| ruf | A list of URIs for ISPs to send forensic reports to. NOTE: this is not a list of email addresses. DMARC requires a list of URIs of the form “mailto:test@example.org”. |
| rf | The reporting format for forensic reports. This can be either “afrf” or “iodef”. |
| pct | The percentage tag instructs ISPs to only apply the DMARC policy to a percentage of failing email’s. “pct=50” will tell receivers to only apply the “p=” policy 50% of the time against emails that fail the DMARC check. NOTE: this will not work for the “none” policy, but only for “quarantine” or “reject” policies. |
| adkim | Specifies the “Alignment Mode” for DKIM signatures and can be either “r” (Relaxed) or “s” (Strict). In Relaxed mode, authenticated DKIM signing domains (d=) that share an Organizational Domain with an emails ‘From’ domain will pass the DMARC check. In Strict mode an exact match is required. |
| aspf | Specifies the “Alignment Mode” for SPF and can be either “r” (Relaxed) or “s” (Strict). In Relaxed mode, authenticated SPF domains that share an Organizational Domain with an emails ‘From’ domain will pass the DMARC check. In Strict mode an exact match is required. |
| sp | This policy should be applied to email from a sub-domain of this domain that fails the DMARC check. Using this tag, domain owners can publish a “wildcard” policy for all subdomains. |
| fo | Forensic options. Allowed values: “0” to generate reports if both DKIM and SPF fail, “1” to generate reports if either DKIM or SPF fails to produce a DMARC pass result, “d” to generate report if DKIM has failed or “s” if SPF failed. |
| ri | The reporting interval for how often you would like to receive aggregate XML reports. This is a preference and ISPs could (and most likely will) send the report at different intervals (normally this will be daily). |