DomainKeys Class
Provides methods for signing e-mails with DomainKeys and DKIM signatures and verifying signatures of incoming e-mails.
Inheritance Hierarchy
SystemObject
  MailBee.SecurityDomainKeys

Namespace: MailBee.Security
Assembly: MailBee.NET (in MailBee.NET.dll) Version: 11.2.0 build 590 for .NET 4.5
Syntax
public class DomainKeys

The DomainKeys type exposes the following members.

Constructors
  NameDescription
Public methodDomainKeys
Initializes a new instance of DomainKeys class.
Public methodDomainKeys(Boolean)
Initializes a new instance of DomainKeys class for use in web applications.
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Methods
  NameDescription
Public methodEquals
Determines whether the specified object is equal to the current object.
(Inherited from Object.)
Protected methodFinalize
Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.
(Inherited from Object.)
Public methodGetHashCode
Serves as the default hash function.
(Inherited from Object.)
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Protected methodMemberwiseClone
Creates a shallow copy of the current Object.
(Inherited from Object.)
Public methodCode exampleSign(MailMessage, String, Byte, String)
Signs a mail message with DomainKeys and DKIM signatures.
Public methodSign(MailMessage, String, Byte, String, DomainKeysTypes)
Signs a mail message with DomainKeys and/or DKIM signatures.
Public methodCode exampleSign(MailMessage, String, String, Boolean, String)
Signs a mail message with DomainKeys and DKIM signatures.
Public methodSign(MailMessage, String, String, Boolean, String, DomainKeysTypes)
Signs a mail message with DomainKeys and/or DKIM signatures.
Public methodToString
Returns a string that represents the current object.
(Inherited from Object.)
Public methodCode exampleVerify(MailMessage, Smtp)
Verifies the DomainKeys and DKIM signatures of the mail message.
Public methodCode exampleVerify(MailMessage, Smtp, Header)
Verifies the specified DomainKeys and/or DKIM signature of the mail message.
Public methodVerify(MailMessage, Smtp, DomainKeysTypes)
Verifies the DomainKeys and/or DKIM signatures of the mail message.
Public methodVerifyAsync(MailMessage, Smtp)
async/await version of Verify(MailMessage, Smtp).
Public methodVerifyAsync(MailMessage, Smtp, Header)
async/await version of Verify(MailMessage, Smtp, Header).
Public methodVerifyAsync(MailMessage, Smtp, DomainKeysTypes)
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Properties
  NameDescription
Public propertyLastResult
Gets a numeric code of the last error.
Public propertyCode exampleThrowExceptions
Gets or sets whether the object will throw exceptions on errors.
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Remarks
This class serves two purposes:
  • Signing e-mails to be sent out with DomainKeys (and/or DKIM) signature. The domain you're sending from (i.e. company.com if the From: address is j.doe@company.com) should have valid DomainKeys DNS TXT records containing the public key of your domain (this record should be placed not directly for sending domain but rather for its sub-domain called selector). The e-mails are signed with the private key for this domain. You can use Sign(MailMessage, String, String, Boolean, String) method and its overloads to sign messages with your private key. This method also accepts selector parameter so that you can use any name for selector sub-domain. For instance, Gmail currently uses "gamma" as selector value so that the entire DomainKeys domain name is "gamma._domainkey.gmail.com" where "._domainkey." suffix is predefined by DomainKeys standard. It's important to understand there can be no actual host under that name, it's just a DNS record.
  • Verifying DomainKeys (and/or DKIM) signatures of e-mails you receive. This involves using Smtp component for retrieving DomainKeys DNS record of the domain which sent the e-mail message in question, extracting the public key from that DNS record, and testing whether the signature matches that public key. No special DNS records are required on the receiving domain. Thus, you can always verify DomainKeys signatures regardless whether your domain has DomainKeys DNS record or not.

If your domain does not have the necessary DNS TXT record holding DomainKeys data, you need to create one or contact your server administrator on this matter. You can create a public/private key pair with a tool such as OpenSSL. With OpenSSL, be sure to set the private key length to 1024 bits or more (DKIM itself does work with weaker keys but some providers like Gmail will not accept them). See RFC 4870 for more information on creating these keys.

Note Note
This class supports classic DomainKeys (DK) and newer DKIM technology. DK is always supported while DKIM support may require the system to support SHA256 algorithm. In case of a FIPS-compliant system, you should enable FipsMode and make sure you're using MailBee.NET.dll for .NET 4.0+. Read more on on SHA256 availability in DomainKeysVerifyResult topic.

Although DK and DKIM are different technologies, DKIM uses the same DNS records, public/private keys and selectors as DK. Thus, checking both DK and DKIM signatures won't force Verify(MailMessage, Smtp) method to send two DNS queries (for DK and DKIM). Only a single query regarding DomainKeys record will be made.

Examples
See Also