dropbox.com
Receivers are told to reject mail that fails authentication for this domain.
Receivers are told to reject mail that fails authentication for this domain. Keep watching aggregate reports so a new sending service does not silently start failing.
Score held up: DMARC is enforcing at p=reject, so nobody else can send as this domain. That is the hard part, and it is done. What is left below is about your own mail arriving, not about anyone spoofing you.
138 DNS queries · 2516 ms
- 1Could not verify DKIM signing for Google WorkspaceConfirm DKIM is switched on in Google Workspace, then add your selector here so every future scan can verify it directly.
- 2Selector 'm1' uses a 1024-bit RSA keyRotate to 2048-bit at your next key rotation.
- 3CAA has no reporting addressAdd a record such as: 0 iodef "mailto:[email protected]"
- 4No explicit subdomain policy (sp=)Consider adding 'sp=reject' if no subdomain sends mail.
Identity ·Sending services detected
Read from your SPF includes and MX hosts, then checked for a published DKIM key.
Identity ·DMARC
- Policy
- reject
- Coverage
- 100%
- Alignment
- dkim=r spf=r
Identity ·DKIM
111 selectors probed
m1MarketoRSA 1024zendesk1ZendeskRSA 2048zendesk2ZendeskRSA 2048Identity ·SPF
Worst-case evaluation across every include.
- include:amazonses.com
- include:_spf.google.com
- include:mail.zendesk.com
- include:mktomail.com
- include:rp.oracleemaildelivery.com
- include:1amer.rp.oracleemaildelivery.com
Findings (10)
MediumCould not verify DKIM signing for Google Workspace›
Google Workspace was detected via SPF include:_spf.google.com, so it is authorised to send mail as dropbox.com. We checked the selectors it uses by default (google, google2048) and found no key. Google Workspace lets you choose your own selector name, so this may simply mean yours is custom. If signing genuinely is not enabled, mail through this service will fail DMARC once forwarded.
Confirm DKIM is switched on in Google Workspace, then add your selector here so every future scan can verify it directly.
RFC 6376
MediumSelector 'm1' uses a 1024-bit RSA key›
1024-bit is the RFC 8301 floor, not a good target. 2048-bit is the current recommendation and is universally supported.
Rotate to 2048-bit at your next key rotation.
RFC 8301
LowNo explicit subdomain policy (sp=)›
Subdomains inherit p=, which is usually what you want. Setting 'sp=reject' explicitly protects unused subdomains even while the parent is still at p=none.
Consider adding 'sp=reject' if no subdomain sends mail.
LowSPF ends in '~all' (softfail)›
Softfail is the correct setting while you are still discovering senders, but it asks receivers to accept unauthorised mail and merely note it.
Once your aggregate reports show no unexplained legitimate sources, tighten to '-all'.
LowSPF record is unusually long›
The record is 562 characters. Very long records risk DNS responses that fall back to TCP, which some resolvers handle poorly.
Consolidate ip4 ranges with wider CIDR blocks where safe.
LowNo MTA-STS policy›
Without MTA-STS, mail to your domain can be downgraded to plaintext by an active network attacker, because SMTP's STARTTLS is opportunistic by default.
Publish a TXT record at _mta-sts.dropbox.com and a policy file at https://mta-sts.dropbox.com/.well-known/mta-sts.txt.
RFC 8461
LowNo TLS-RPT record›
Sending servers have no address to report TLS failures on mail to your domain, so transport problems stay invisible to you until someone complains.
Publish 'v=TLSRPTv1; rua=mailto:<address>' at _smtp._tls.dropbox.com.
RFC 8460
LowCAA has no reporting address›
You have restricted which authorities may issue certificates, but nobody is told when one refuses a request. An iodef address turns an attempted mis-issuance into an alert instead of a silent event.
Add a record such as: 0 iodef "mailto:[email protected]"
RFC 8659
InfoAmazon SES uses selectors we cannot discover›
Detected via SPF include:amazonses.com. SES generates a random per-identity selector when Easy DKIM is enabled, so it cannot be discovered from DNS. Check the SES console for your selector. We cannot confirm or rule out DKIM signing for this service from DNS alone.
Add your Amazon SES selector so we can verify it on every scan.
InfoZone is not signed with DNSSEC›
This is the common case and not a misconfiguration -- most working mail domains are unsigned. It is worth knowing because your authentication records are only as trustworthy as the DNS answers carrying them, and because DNSSEC is the prerequisite for DANE.
If your DNS provider supports one-click DNSSEC, enabling it is low risk. If it does not, this is not worth changing providers over.
RFC 4033
Show 11 passing checks
PassAggregate reporting is configured›
Aggregate reports are requested at: [email protected], [email protected].
PassExternal report destination rua.dmarc.emailanalyst.com is correctly authorised›
Authorised by dropbox.com._report._dmarc.rua.dmarc.emailanalyst.com
PassDMARC policy is p=reject›
Mail failing authentication is rejected outright. This is the correct end state.
PassSPF lookup count is healthy (7/10)›
Worst-case evaluation stays within the limit with headroom to spare.
PassAdobe Marketo's DKIM key is published at m1._domainkey›
Detected via SPF include:mktomail.com. A valid public key for this service is published at m1._domainkey.dropbox.com.
PassZendesk's DKIM keys are published at zendesk1._domainkey, zendesk2._domainkey›
Detected via SPF include:mail.zendesk.com. A valid public key for this service is published at zendesk1._domainkey.dropbox.com, zendesk2._domainkey.dropbox.com.
Pass3 DKIM key(s) published›
Found at: m1, zendesk1, zendesk2.
PassSelector 'zendesk1' uses a 2048-bit RSA key›
Key length meets current guidance.
PassSelector 'zendesk2' uses a 2048-bit RSA key›
Key length meets current guidance.
PassBIMI is published with a certificate reference›
The record at default._bimi.dropbox.com names a logo and a Verified Mark Certificate (a=), and DMARC is enforcing, which BIMI requires. We read the record only; the logo and certificate themselves were not fetched or checked.
PassCertificate issuance is restricted by CAA›
Only amazonaws.com, digicert.com, letsencrypt.org may issue certificates for this domain, so a certificate for your mail hosts or your MTA-STS policy endpoint from any other authority would be a mis-issuance.
RFC 8659
Transport and zone
Where your mail lands, and whether the DNS carrying your records can be trusted.
This is the configuration. It is not the whole picture.
A DNS scan cannot tell you whether dropbox.com’s mail actually aligns, because alignment is decided per message at the receiver. Collect DMARC aggregate reports to see every source sending as this domain.