mobile.de

mobile.de · Last checked 2026-10-04 02:07 UTC

mobile.de

Good, with 2 things to fix

mobile.de scored 80/100 (grade B). The main issues are no DKIM key found for the common selectors and SPF has too many lookups that return nothing. Detected senders: SendGrid.

Checked 2026-10-04 02:07 UTC · fresh check

1 passed2 need attention0 failing5 for informationDetected senders: SendGrid

All checks

MXCan servers find your inbox?Only one MX hostInfo
  • Info: Only one MX host

    All mail for mobile.de goes to mx.sendgrid.net. Most hosted providers make that one name highly available; if you run your own server, consider a backup MX.

SPFWho may send as you?SPF has too many lookups that return nothingNeeds attention
  • Warning: SPF has too many lookups that return nothing

    Checking mail from mobile.de, IPv6 clients would hit 3 void lookups (DNS queries that return no data). RFC 7208 lets receivers fail SPF after 2. Remove includes and mechanisms that point at names that no longer exist, or MX hosts without an address for that family.

  • Info: SPF ends in softfail (~all)

    "~all" is common and works well with DMARC. "-all" is stricter; switch when you are sure every sender is listed.

DKIMAre your emails signed?No DKIM key found for the common selectorsNeeds attention
  • Warning: No DKIM key found for the common selectors

    None of the 47 selectors probed under mobile.de publish a DKIM key. DNS cannot list selectors, so a key under a custom selector may exist: find the s= value in the DKIM-Signature header of a message you sent and check that selector. If DKIM is not set up, enable it at each service that sends mail for mobile.de.

DMARCWhat happens to fakes?No issues foundPass

Nothing to report.

AlignmentDoes it match your From?SPF alignment is unknownInfo
  • Info: SPF alignment is unknown

    The SPF record of mobile.de can pass for some senders (those matched before the failing part), but another evaluation path ends in a permanent error (spf.void-lookups). Senders that reach that path fail SPF, so whether your mail aligns through SPF is unknown. Fix the error so every path evaluates.

BIMICan inboxes show your logo?No BIMI recordInfo
  • Info: No BIMI record

    No BIMI record at default._bimi.mobile.de. BIMI is optional: it shows your logo next to your mail in supporting inboxes once DMARC is enforced.

    How to fix this
MTA-STSIs mail to you encrypted?No MTA-STS recordInfo
  • Info: No MTA-STS record

    No MTA-STS record at _mta-sts.mobile.de. MTA-STS (RFC 8461) makes sending servers require TLS and a valid certificate when delivering to you, which blocks downgrade attacks.

    How to fix this
TLS-RPTWill you hear about failures?No TLS-RPT recordInfo
  • Info: No TLS-RPT record

    No TLS reporting record at _smtp._tls.mobile.de. TLS-RPT (RFC 8460) tells senders where to send daily reports about failed encrypted deliveries to you.

    How to fix this

How to fix it

Enable DKIM for SendGridinstruction

SendGrid generates the DKIM key for each account, so the exact record must come from SendGrid. Without DKIM, mail it sends for mobile.de cannot pass DMARC through DKIM.

Applies to: s1._domainkey.mobile.de

  1. In SendGrid, enable DKIM signing for mobile.de: account-specific: copy the CNAME/TXT from the SendGrid dashboard. Publish exactly the record SendGrid shows (TXT or CNAME) at the host name it gives, then turn signing on. Instructions: https://docs.sendgrid.com/ui/account-and-settings/how-to-set-up-domain-authentication

Enable DKIM for SendGridinstruction

SendGrid generates the DKIM key for each account, so the exact record must come from SendGrid. Without DKIM, mail it sends for mobile.de cannot pass DMARC through DKIM.

Applies to: s2._domainkey.mobile.de

  1. In SendGrid, enable DKIM signing for mobile.de: account-specific: copy the CNAME/TXT from the SendGrid dashboard. Publish exactly the record SendGrid shows (TXT or CNAME) at the host name it gives, then turn signing on. Instructions: https://docs.sendgrid.com/ui/account-and-settings/how-to-set-up-domain-authentication

Publish the MTA-STS recordTXT

Tells sending servers that mobile.de publishes an MTA-STS policy at https://mta-sts.mobile.de/.well-known/mta-sts.txt. Change the id whenever the policy file changes.

TypeTXT
Name / Host
_mta-sts.mobile.de

Some DNS providers want just “_mta-sts” here.

Value
v=STSv1; id=202610040207

Host the MTA-STS policy filepolicy-file

Serve this file over HTTPS with a valid certificate for mta-sts.mobile.de. It lists your MX hosts and starts in testing mode; switch to mode: enforce once TLS-RPT reports show no failures.

Location
https://mta-sts.mobile.de/.well-known/mta-sts.txt
Contents
version: STSv1
mode: testing
mx: mx.sendgrid.net
max_age: 604800

Set up a TLS report addressinstruction

Sending servers will report TLS failures when delivering to mobile.de, which you need before enforcing MTA-STS. The address must accept TLS reports; a DMARC report address does not necessarily do so.

Applies to: _smtp._tls.mobile.de

  1. Pick an address that will receive TLS reports: a mailbox you read (for example tls-reports@mobile.de, created first) or a TLS reporting service. 2. Publish a TXT record at _smtp._tls.mobile.de with the value v=TLSRPTv1; rua=mailto:<that address>.

Prepare BIMIinstruction

BIMI shows your logo next to messages in supporting inboxes, but only for mail that passes DMARC under an enforced policy.

Applies to: default._bimi.mobile.de

  1. Enforce DMARC first: p=quarantine or p=reject at 100% (no pct below 100). 2. Convert your logo to an SVG Tiny PS file and host it over HTTPS, for example https://mobile.de/bimi/logo.svg. 3. For Gmail and Apple Mail, obtain a VMC or CMC certificate for the logo. 4. Publish a TXT record at default._bimi.mobile.de with v=BIMI1, l= set to the logo URL and a= set to the certificate URL.