This is a class library for validating SPF records.
Stable builds are available as NuGet packages. You can install it via the Package Manager or via the Package Manager Console:
Install-Package Workshell.SPF
You can use the SPF validator like so:
var validator = new SPFValidator();
var result = await validator.ValidateAsync("gmail.com", IPAddress.Parse("209.85.161.51")); // There's a sync version too
The result is a value from the SPFResult enum:
| Value | Meaning |
|---|---|
| None | No records were published by the domain or that the domain couldn't be determined |
| Neutral | The domain owner has explicitly stated that he cannot or does not want to assert whether or not the IP address is authorized. |
| Pass | The client is authorized to inject mail with the given identity. |
| Fail | The client is not authorized to use the domain in the given identity. |
| SoftFail | The domain believes the host is not authorized but is not willing to make that strong of a statement. |
| TempError | A temporary error was encountered. |
| PermError | A permenant error was encountered. |
The SPF validator depends on the excellent DnsClient for servicing DNS requests. If you use the default constructor in SPFValidator then a new instance of LookupClient will be created for each instance of the validator.
However, they recommend you create a single instance and share it across all requests. To that end we also have a constructor that takes an ILookupClient which can be manually supplied or used with DI.
For example:
var lookupClient = new LookupClient();
var validator = new SPFValidator(lookupClient);
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