Мне нужно было установить для ValidateRequest значение false в директиве страницы.
Пример кода -
sms.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="sms.aspx.cs" EnableEventValidation="false" ValidateRequest="false" Inherits="sms" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<p>SMS</p>
</form>
</body>
</html>
sms.aspx.cs
public partial class sms : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string subject = Request.Params["subject"];
string message = Request.Params["body-plain"];
using (SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["YOURCONNECTIONSTRING"].ConnectionString))
{
cn.Open();
using (SqlCommand cm = cn.CreateCommand())
{
cm.CommandType = CommandType.Text;
cm.CommandText = "INSERT INTO SMS (subject, message, DateTime) VALUES (@Subject, @Message, @Dateandtime);";
cm.Parameters.Add("@Subject", SqlDbType.NVarChar).Value = subject;
cm.Parameters.Add("@Message", SqlDbType.NVarChar).Value = message;
cm.Parameters.Add("@Dateandtime", SqlDbType.DateTime).Value = DateTime.Now.ToString();
SqlDataReader dr = cm.ExecuteReader();
dr.Dispose();
cm.Dispose();
}
}
}
}
Надеюсь, это поможет кому-то еще, использующему Mailgun и C #.