how to send email from ELMAH?

I'm trying to configure ELMAH to send emails but I'm getting the following error:

Server Error in '/' Application.

The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Must issue a STARTTLS command first. 59sm11486886otw.9 - gsmtp

I've seen several posts for this same error but none of the suggestions have worked.

ELMAH is logging errors to SQL Server.

Additionally, I am able to send SMTP mail using the same credentials that ELMAH uses so I don't think I have an authentication error:

MailMessage mailx = new MailMessage();
mailx.To.Add("mySendTo");
mailx.From = new MailAddress("mySendFrom");
mailx.Subject = "My Subject";
mailx.Body = string.Format("My email body");
mailx.IsBodyHtml = true;

SmtpClient smtpx = new SmtpClient();
smtpx.Host = "smtp.gmail.com";
smtpx.Port = 587;
smtpx.UseDefaultCredentials = false;
smtpx.Credentials = new System.Net.NetworkCredential("MyLoginUser", "MyLoginPwd");
smtpx.EnableSsl = true;
smtpx.Send(mailx);

Web.Config contains the folowing ELMAH information:

<configuration>
  <configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    <sectionGroup name="elmah">
      <section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah" />
      <section name="errorLog" requirePermission="false" type="Elmah.ErrorLogSectionHandler, Elmah" />
      <section name="errorMail" requirePermission="false" type="Elmah.ErrorMailSectionHandler, Elmah" />
      <section name="errorFilter" requirePermission="false" type="Elmah.ErrorFilterSectionHandler, Elmah" />
    </sectionGroup>
  </configSections>

  <appSettings>
    <add key="elmah.mvc.disableHandler" value="false" />
    <add key="elmah.mvc.disableHandleErrorFilter" value="false" />
    <add key="elmah.mvc.requiresAuthentication" value="true" />
    <add key="elmah.mvc.IgnoreDefaultRoute" value="false" />
    <add key="elmah.mvc.allowedRoles" value="*" />
    <add key="elmah.mvc.allowedUsers" value="[email protected], [email protected]" />
    <add key="elmah.mvc.route" value="elmah" />
    <add key="elmah.mvc.UserAuthCaseSensitive" value="true" />
  </appSettings>

  <httpModules>
    <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" />
    <add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" />
    <add name="ErrorFilter" type="Elmah.ErrorFilterModule, Elmah" />
  </httpModules>

  <modules>
    <remove name="FormsAuthentication" />
    <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" preCondition="managedHandler" />
    <add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" preCondition="managedHandler" />
    <add name="ErrorFilter" type="Elmah.ErrorFilterModule, Elmah" preCondition="managedHandler" />
    </modules>

  <system.net>
    <mailSettings>
      <smtp deliveryMethod="Network">
        <network host="smtp.gmail.com" port="587" userName="MyUserName" password="MyUserPwd" defaultCredentials="false"/>
      </smtp>
    </mailSettings>
  </system.net>

  <elmah>
    <errorLog type="Elmah.SqlErrorLog, Elmah" connectionStringName="DefaultConnection" />
    <security allowRemoteAccess="yes" />   

    <errorMail
        from="[email protected]" to="mySendTo" subject="MySubject" async="false" smtpPort="587" useSSL="true"/>
  </elmah>

</configuration>

The ELMAH version in use is 1.2.13605.0

I have tried it in the Dev Environment, which does not utilize SSL and in the in the Test Environment, which has an SSL cert. Both having same error.

I have tried many of the recommendations found in SO posts but none have worked. Here are some of them:
Unable to configure mail for Elmah
Send email from Elmah?
Elmah not sending Email
elmah - cannot email exceptions

Solution

I'm not sure if it fixes your problem, but I tried validating your web.config using the ELMAH Configuration Validator. It gives the following result:

The 'allowRemoteAccess' attribute is invalid - The value 'yes' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:boolean' - The string 'yes' is not a valid Boolean value.
The 'useSSL' attribute is not declared.

You can consider changing the allowRemoteAccess to 'true', but 'yes' probably works as well. What I'm looking at in the result, is the 'useSSL' attribute. Try renaming that to 'useSsl' and see if that works. The validator accepts 'useSsl' but not 'useSSL'.