Summary
- Registrar
- Cloudflare, Inc.
- Status
- clientDeleteProhibited
- Created on
- July 7, 2014
- Expires on
- July 7, 2027
- Name servers
- owen.ns.cloudflare.com, vera.ns.cloudflare.com
- Mail servers
- aspmx.l.google.com, alt1.aspmx.l.google.com, alt2.aspmx.l.google.com, aspmx2.googlemail.com, aspmx3.googlemail.com
- DMARC
- Reject
- SPF
- Strict
- DKIM
- 6 keys found
- Website
- See the website
Spoofing protection (DMARC)
E-mails spoofing this domain are rejected.
DMARC tells mail servers what to do with an e-mail that claims to come from letsencrypt.org but fails SPF and DKIM checks.
- Policy
- Reject
- Subdomain policy
- Reject
- Messages covered
- 100%
- DKIM alignment
- Relaxed
- SPF alignment
- Relaxed
- Aggregate reports
- [email protected]
- Failure reports
- —
Record
v=DMARC1; p=reject; rua=mailto:[email protected]; fo=1
Authorized senders (SPF)
E-mails sent by any other server are rejected.
SPF lists the servers allowed to send e-mails for letsencrypt.org.
| Rule | Value | Result |
|---|---|---|
| include | _spf.google.com | Allowed |
| ip4 | 23.178.112.0/24 | Allowed |
| ip4 | 66.133.109.36 | Allowed |
| ip4 | 64.78.152.132 | Allowed |
| include | mail.zendesk.com | Allowed |
| include | _spf.intacct.com | Allowed |
| all | — | Rejected |
Top-level DNS lookups: 3 of 10 allowed
Record
v=spf1 include:_spf.google.com ip4:23.178.112.0/24 ip4:66.133.109.36 ip4:64.78.152.132 include:mail.zendesk.com include:_spf.intacct.com -all
E-mail signing (DKIM)
DKIM keys published by letsencrypt.org under the most common selectors. Other keys may exist under selectors specific to each sending service.
| Selector | Likely service | Key | Status |
|---|---|---|---|
| Google Workspace | RSA 1024 bits · short | Active | |
| k2 | Mailchimp | RSA 2048 bits | Active |
| k3 | Mailchimp | RSA 2048 bits | Active |
| mandrill | Mandrill | RSA 1024 bits · short | Active |
| zendesk1 | Zendesk | RSA 2048 bits | Active |
| zendesk2 | Zendesk | RSA 2048 bits | Active |
RSA keys shorter than 2048 bits, called short keys, are discouraged: they are easier to break.
MX, SPF, DKIM and DMARC: the e-mail records
Four DNS records make a domain's e-mail work. MX says where e-mails sent to letsencrypt.org arrive; SPF, DKIM and DMARC let mail servers check that an e-mail claiming to come from letsencrypt.org was really sent by this domain, which protects it against spoofing.
MX
An MX (Mail Exchanger) record designates a server that receives e-mails sent to the domain. When someone writes to an @letsencrypt.org address, their mail server queries the DNS for the domain's MX records, then delivers the message to the server they point to.
Example record
letsencrypt.org MX 10 mx1.letsencrypt.org. letsencrypt.org MX 20 mx2.letsencrypt.org.
What the record contains
- 10, 20
- Priority: the server with the lowest number is tried first. Servers with equal priority share the load.
- mx1.letsencrypt.org.
- Host name of the mail server. It must point to an A or AAAA record: an IP address or an alias (CNAME) is not allowed here.
- 0 .
- An MX "0 .", called a null MX, declares that the domain accepts no e-mail: sending servers give up at once instead of retrying.
Declaring at least two servers with different priorities avoids losing e-mails during an outage: sending servers retry for several days and fall back on the backup server. Without any MX, they try to deliver directly to the IP address of the domain.
SPF
SPF (Sender Policy Framework) is a TXT record listing the servers allowed to send e-mails on behalf of the domain. The receiving server checks that the sender is on this list. The final "all" rule says what to do with other servers: reject them (-all), flag their e-mails as suspicious (~all) or make no decision (?all).
Example record
letsencrypt.org TXT "v=spf1 mx include:_spf.google.com ip4:192.0.2.10 -all"
What the record contains
- v=spf1
- Identifies the record as an SPF policy. It must come first.
- ip4, ip6
- Allows a specific IP address or an address range, for example ip4:192.0.2.0/24.
- a, mx
- Allows the addresses of the domain itself (A record) or those of its mail servers (MX).
- include
- Allows the servers of another domain, usually a sending service: include:_spf.google.com for Google Workspace.
- -all, ~all
- Final rule, applied to every other server. Its qualifier decides what happens to them: - rejects them, ~ flags their e-mails as suspicious, ? makes no decision, + accepts them (avoid it).
A domain must publish only one SPF record, and its evaluation cannot exceed 10 DNS lookups (include, a, mx, exists, redirect). Beyond that, mail servers treat it as invalid.
DKIM
DKIM (DomainKeys Identified Mail) signs every outgoing e-mail with a private key. The matching public key is published in a TXT record at selector._domainkey.letsencrypt.org, so the recipient can check that the message really comes from the domain and was not altered on the way. The selector is chosen by each sending service and cannot be guessed: Dataweaz checks the most common ones (Google Workspace, Microsoft 365, Mailchimp, SendGrid…), so a key published under another selector may exist without appearing here.
Example record
google._domainkey.letsencrypt.org TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA…"
What the record contains
- v=DKIM1
- Protocol version. Optional but recommended, in which case it must come first.
- k
- Key algorithm: rsa, the most common, or ed25519.
- p
- Public key, base64-encoded. An empty value means the key has been revoked.
- t
- Flags: y marks a key in testing, whose failures must not be penalized; s forbids its use for subdomains.
Each sending service publishes its key under its own selector (google, selector1, k1…), which allows several keys and seamless rotation. A 2048-bit RSA key is recommended today.
DMARC
DMARC (Domain-based Message Authentication, Reporting and Conformance) builds on SPF and DKIM. Published on _dmarc.letsencrypt.org, it tells mail servers what to do with an e-mail that fails these checks (let it through, send it to spam or reject it) and where to send reports.
Example record
_dmarc.letsencrypt.org TXT "v=DMARC1; p=quarantine; rua=mailto:[email protected]; adkim=r; aspf=r"
What the record contains
- v=DMARC1
- Identifies the record as a DMARC policy. It must come first.
- p
- Policy applied to e-mails that fail the checks: none (monitoring only), quarantine (spam folder) or reject.
- sp
- Subdomain policy. Without it, subdomains follow the domain's policy.
- rua
- Address that receives daily aggregate reports about e-mails sent on behalf of the domain, whether they pass the checks or not.
- ruf
- Address that receives detailed failure reports, message by message. Few providers still send them.
- pct
- Percentage of e-mails subject to the policy, for a gradual rollout. 100 by default.
- adkim, aspf
- DKIM and SPF alignment: r (relaxed, a subdomain of the same domain is enough) or s (strict, the domain must be identical).
To roll out DMARC without blocking legitimate e-mails, start with p=none and an rua address, analyze the reports to find every service sending on behalf of the domain, then move to quarantine and finally to reject.
DNS records of letsencrypt.org
IP addresses (A and AAAA)
An A record maps the domain name to an IPv4 address: the address of the server that browsers contact to display the website. The AAAA record does the same for an IPv6 address. A domain can have several of them to spread visits across several servers.
| Type | IP address |
|---|---|
| A | 35.157.26.135 |
| A | 63.176.8.218 |
| AAAA | 2a05:d014:58f:6200::259 |
| AAAA | 2a05:d014:58f:6200::258 |
Name servers (NS)
NS records designate the authoritative DNS servers of the domain: they answer every question about its other records (A, MX, TXT…). They are provided by the registrar, the hosting provider or a dedicated DNS service, and several servers are declared so that the domain keeps working if one of them fails.
| Server | IP address |
|---|---|
| owen.ns.cloudflare.com | 108.162.193.219 |
| vera.ns.cloudflare.com | 172.64.32.147 |
Mail servers (MX)
MX records point to the servers that receive e-mails sent to the domain, that is to @letsencrypt.org addresses. Each server has a priority: the one with the lowest number is tried first, the others take over if it fails. Without an MX record, the domain cannot receive e-mails.
| Priority | Server | IP address |
|---|---|---|
| 1 | aspmx.l.google.com | 74.125.206.26 |
| 5 | alt1.aspmx.l.google.com | 192.178.213.27 |
| 5 | alt2.aspmx.l.google.com | 142.251.127.26 |
| 10 | aspmx2.googlemail.com | 192.178.213.26 |
| 10 | aspmx3.googlemail.com | 142.251.127.27 |
TXT records
TXT records hold free text. They are used to prove ownership of the domain to online services (Google, Microsoft, Facebook…) and to publish e-mail security rules: SPF on the domain itself, DMARC on _dmarc.letsencrypt.org.
| Name | Content |
|---|---|
| letsencrypt.org | pardot1011011=d160caff32c4415bb46bb82d8c50e5bea7ea1a74f5a149cb96bd952467266044 |
| letsencrypt.org | sending_domain1011011=f98c68e7636a708a1987c7b9da300d64a354041fa41ea2039fbb02bc18c4ed0f |
| letsencrypt.org | v=spf1 include:_spf.google.com ip4:23.178.112.0/24 ip4:66.133.109.36 ip4:64.78.152.132 include:mail.zendesk.com include:_spf.intacct.com -all |
| letsencrypt.org | anthropic-domain-verification-eer9ky=uy5e3EOy8j15k1u9UesevyP1N |
| _dmarc.letsencrypt.org | v=DMARC1; p=reject; rua=mailto:[email protected]; fo=1 |
| google._domainkey.letsencrypt.org | v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCEBV+uacEmkQqqZMwwF+Kv6oEvaPy/zDOancu+DAemWPty49Sc3PR7n+Il8JGnz8j0Ldv95ch9SGNVuvvRh5PRdoPdNsFjrfkxvSQsC7r1fXMxo2/QnYCTA9f42LB1PMgCUaqKPE3muAUWVq+6w07UTyrY9nCvtuXNm4GZvfAbfwIDAQAB |
| k2._domainkey.letsencrypt.org | v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAv2aC2KjGKLOwTweBY5A9RpjsxaBXR9r7OAU6U8/zn92ivImI75naUujWbItRI/QmL1jy5PWGqLwoUA0b90ObWaLDc+i9MtTNmGeWO009hr20fIxhGg6XBT2kjZ1DTThopSe1nAndsupmcBwlQ5Q6LJ+ZAxLcujnPIxM0ZBLmgpkv8u6RfY4eFP8OLvdAW3oSuB0DyLDigQX4Sj8wBO4YIdQH6AAmBeOsidsKAFNFUCpc3vCxtBDR12U+cBg724l3sBkMQ8evnz6idnqxq9QAVYh8k4kJ+RP+6cqTdy7LjIm8xY/bQNpQIpGUAuDo2DjLcCDun9DAI4Q/3z+Q0o9QuQIDAQAB; |
| k3._domainkey.letsencrypt.org | v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsYGiMSn7fsUqSvfSX40x9R1OlRtbNiCY80lHRIlcKx3XDIR7257aUx+q9CSIARdfTL6KCuLGNFx5g9TgVr6png4ajcieSQGtOehBgxnkDN8aAA5TX0FmFrcefJU0JoxLOF09EKgXxhSSHCk/ekVb0PXSboHXoZ9+EI404F1qhcwXXIgHXTaUthHTut2P6BBZhIXIgvDe/w49GchR7MRJqjNb7neEBbYHbgWuBTvvHCg7Gy6m6n9krYK+ROWq3dVvXy9plAGK3ygM+HtjIiMt7arRGMOF0WgDTz7YdN9BGpt6BvXxLnjiQcgS5T9n+cIyPZgiWzDMXNlaEEdKTEKxrwIDAQAB; |
| mandrill._domainkey.letsencrypt.org | v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCrLHiExVd55zd/IQ/J/mRwSRMAocV/hMB3jXwaHH36d9NaVynQFYV8NaWi69c1veUtRzGt7yAioXqLj7Z4TeEUoOLgrKsn8YnckGs9i3B3tVFB+Ch/4mPhXWiNfNdynHWBcPcbJ8kjEQ2U8y78dHZj1YeRXXVvWob2OaKynO8/lQIDAQAB |
| zendesk1._domainkey.letsencrypt.org | v=DKIM1;t=s;n=core;k=rsa;p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA9IqdLrO3Zr2/56MHt8oQVCQorP0Bl2Fz9sM2tFBnJCdB/HogQmuudEg2xAovCN2PYpw44UijIvPuBoT9vxiv6ZCBJTLJXa82r6ke5rE4tbe9NKFIrVIb9S306cJDrnKFMDb8p0dU/Su0+eUR5gVAOtCuz2L8HAzs5edvsEvD/Fb4ny1RLNSEPZkIQLfGhVxQeWANm3+1Jwb/OBVXV9k0nKpWrpgqcmO7NzroJirp014RQY7rGi60JLUubc6XhvoFQBQrtOAdVlZC5wvfS1bgpq5kQpdP7cajIqWCeqxPTeo0ZUpey2ZcaygEsZz0Z3Gs5wDzyuqd7/ADpr2jNF7ozwIDAQAB |
| zendesk2._domainkey.letsencrypt.org | v=DKIM1; t=s; n=core; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAmiSFNkgXrO3I8aOaPONDZWHv027rkiGIwb838OyXPgvFDEkCV/qGcdXSjZnaVAadrTm/oKnL8WOltP9zB1FLEuKt0fTi5zRyKPE4oIYCnEzXwrGqzjUcCABQBawQVqvXjDOaYh9Lhp8W5PYOLo905vRW7ipyIMDhuzBOJls91/WWXnNK0OwP3RghiisZjA3K2KqtRwf7w6GjNeNuAMNhvcmgAN15d/mhK+dev/hcRbal66RoYyTD8c0F0isahWH0envEX8aj+SBhheNk0/U37dGE+4nFaY5yP9CUlYjFKDSIKZgHzG4Hci3t/RubU58pi6BCrQQdAFvIOeDFeCZ0ywIDAQAB |
Related IP addresses
IPv4 addresses used by letsencrypt.org: website, name servers, mail servers and senders authorized by SPF.
| IP address | Used for | /24 block |
|---|---|---|
| 35.157.26.135 | Website | 35.157.26.0/24 |
| 63.176.8.218 | Website | 63.176.8.0/24 |
| 108.162.193.219 | Name server owen.ns.cloudflare.com | 108.162.193.0/24 |
| 172.64.32.147 | Name server vera.ns.cloudflare.com | 172.64.32.0/24 |
| 74.125.206.26 | Mail server aspmx.l.google.com | 74.125.206.0/24 |
| 192.178.213.27 | Mail server alt1.aspmx.l.google.com | 192.178.213.0/24 |
| 142.251.127.26 | Mail server alt2.aspmx.l.google.com | 142.251.127.0/24 |
| 192.178.213.26 | Mail server aspmx2.googlemail.com | 192.178.213.0/24 |
| 142.251.127.27 | Mail server aspmx3.googlemail.com | 142.251.127.0/24 |
| 66.133.109.36 | Authorized by SPF | 66.133.109.0/24 |
| 64.78.152.132 | Authorized by SPF | 64.78.152.0/24 |
WHOIS of the domain letsencrypt.org
Domain Name: letsencrypt.org Registry Domain ID: REDACTED Registrar WHOIS Server: http://whois.cloudflare.com Registrar URL: http://www.cloudflare.com Updated Date: 2026-08-12T02:12:50Z Creation Date: 2014-07-07T19:54:04Z Registry Expiry Date: 2027-07-07T19:54:04Z Registrar: Cloudflare, Inc. Registrar IANA ID: 1910 Registrar Abuse Contact Email: [email protected] Registrar Abuse Contact Phone: +1.6503198930 Domain Status: clientDeleteProhibited https://icann.org/epp#clientDeleteProhibited Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited Domain Status: clientUpdateProhibited https://icann.org/epp#clientUpdateProhibited Name Server: owen.ns.cloudflare.com Name Server: vera.ns.cloudflare.com DNSSEC: unsigned URL of the ICANN Whois Inaccuracy Complaint Form: https://icann.org/wicf/ >>> Last update of WHOIS database: 2026-10-02T17:54:30Z <<< For more information on Whois status codes, please visit https://icann.org/epp Terms of Use: Access to Public Interest Registry WHOIS information is provided to assist persons in determining the contents of a domain name registration record in the Public Interest Registry registry database. The data in this record is provided by Public Interest Registry for informational purposes only, and Public Interest Registry does not guarantee its accuracy. This service is intended only for query-based access. You agree that you will use this data only for lawful purposes and that, under no circumstances will you use this data to (a) allow, enable, or otherwise support the transmission by e-mail, telephone, or facsimile of mass unsolicited, commercial advertising or solicitations to entities other than the data recipient's own existing customers; or (b) enable high volume, automated, electronic processes that send queries or data to the systems of Registry Operator, a Registrar, or Identity Digital except as reasonably necessary to register domain names or modify existing registrations. All rights reserved. Public Interest Registry reserves the right to modify these terms at any time. By submitting this query, you agree to abide by this policy. The Registrar of Record identified in this output may have an RDDS service that can be queried for additional information on how to contact the Registrant, Admin, or Tech contact of the queried domain name. Domain Name: LETSENCRYPT.ORG Registry Domain ID: D173236842-LROR Registrar WHOIS Server: whois.cloudflare.com Registrar URL: https://www.cloudflare.com Updated Date: 2021-09-15T19:41:24Z Creation Date: 2014-07-07T19:54:04Z Registrar Registration Expiration Date: 2027-07-07T19:54:04Z Registrar: Cloudflare, Inc. Registrar IANA ID: 1910 Domain Status: clientdeleteprohibited https://icann.org/epp#clientdeleteprohibited Domain Status: clienttransferprohibited https://icann.org/epp#clienttransferprohibited Domain Status: clientupdateprohibited https://icann.org/epp#clientupdateprohibited Registry Registrant ID: Registrant Name: DATA REDACTED Registrant Organization: DATA REDACTED Registrant Street: DATA REDACTED Registrant City: DATA REDACTED Registrant State/Province: MN Registrant Postal Code: DATA REDACTED Registrant Country: US Registrant Phone: DATA REDACTED Registrant Phone Ext: DATA REDACTED Registrant Fax: DATA REDACTED Registrant Fax Ext: DATA REDACTED Registrant Email: https://domaincontact.registrar.cloudflare.com/letsencrypt.org Registry Admin ID: Admin Name: DATA REDACTED Admin Organization: DATA REDACTED Admin Street: DATA REDACTED Admin City: DATA REDACTED Admin State/Province: DATA REDACTED Admin Postal Code: DATA REDACTED Admin Country: DATA REDACTED Admin Phone: DATA REDACTED Admin Phone Ext: DATA REDACTED Admin Fax: DATA REDACTED Admin Fax Ext: DATA REDACTED Admin Email: https://domaincontact.registrar.cloudflare.com/letsencrypt.org Registry Tech ID: Tech Name: DATA REDACTED Tech Organization: DATA REDACTED Tech Street: DATA REDACTED Tech City: DATA REDACTED Tech State/Province: DATA REDACTED Tech Postal Code: DATA REDACTED Tech Country: DATA REDACTED Tech Phone: DATA REDACTED Tech Phone Ext: DATA REDACTED Tech Fax: DATA REDACTED Tech Fax Ext: DATA REDACTED Tech Email: https://domaincontact.registrar.cloudflare.com/letsencrypt.org Registry Billing ID: Billing Name: DATA REDACTED Billing Organization: DATA REDACTED Billing Street: DATA REDACTED Billing City: DATA REDACTED Billing State/Province: DATA REDACTED Billing Postal Code: DATA REDACTED Billing Country: DATA REDACTED Billing Phone: DATA REDACTED Billing Phone Ext: DATA REDACTED Billing Fax: DATA REDACTED Billing Fax Ext: DATA REDACTED Billing Email: https://domaincontact.registrar.cloudflare.com/letsencrypt.org Name Server: owen.ns.cloudflare.com Name Server: vera.ns.cloudflare.com DNSSEC: unsigned Registrar Abuse Contact Email: [email protected] Registrar Abuse Contact Phone: +1.4153197517 URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/ >>> Last update of WHOIS database: 2026-10-02T17:54:30Z <<< For more information on Whois status codes, please visit https://icann.org/epp Cloudflare provides more than 13 million domains with the tools to give their global users a faster, more secure, and more reliable internet experience. NOTICE: Data in the Cloudflare Registrar WHOIS database is provided to you by Cloudflare under the terms and conditions at https://www.cloudflare.com/domain-registration-agreement/ By submitting this query, you agree to abide by these terms. Register your domain name at https://www.cloudflare.com/registrar/ % Query time: 713 msec % WHEN: Fri Oct 02 17:54:29 UTC 2026