This page is just a reference of all the known Steam APIs, I do not know how they work. Please do not email me with questions.
UNDOCUMENTEDPOSTSteamGuardPhishingReport

SteamGuardPhishingReport

https://api.steampowered.com/ICredentialsService/SteamGuardPhishingReport/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No
string No
UNDOCUMENTEDPOSTValidateEmailAddress

Validate an email address given a token

https://api.steampowered.com/ICredentialsService/ValidateEmailAddress/v1/
NameValueTypeRequiredDescription
click to setstring Yes Access key
string No