ChangePassword And PasswordRecovery Not Sending Emails

I am using the ASP.NET membership provider controls (ChangePassword and PasswordRecovery) and they generally work just fine. Unfortunately they don't send any emails once the process is finished. I set up the SMTP server using the ASP.NET Configuration Website and it added the following lines to the web.config:

<system.net>
<mailSettings>
<smtp from="maildaemon@pagetailors.de">
<network host="pagetailors.de" password="XXXX" userName="XXXX" />
</smtp>
</mailSettings>
</system.net>

I also tried using the IP adress of the server instead of the domain. In addition to that I set the maildefinition properties on the used web controls:

<MailDefinition From="maildaemon@pagetailors.de"
Subject="Your new password">
</MailDefinition>

Once I finish changing or resetting the password, the controls shows the success message. It does not show any errors but the mails are not sent. I also checked the SMTP log files on the server (it's a MailEnable server) but couldn't even find an attempt to send these messages. I am using a custom email helper class which manually sends an email using the following settings:

public static void SendEmail(string from, string to, string subject, string body)
{
SmtpClient mailClient = new SmtpClient(ConfigReader.GetStringValue("MailServer"));
mailClient.Credentials = new NetworkCredential(ConfigReader.GetStringValue("MailUsername"),
ConfigReader.GetStringValue("MailPassword"));
MailMessage mailMessage = new MailMessage(from, to, subject, body);
mailClient.Send(mailMessage);
}

The values for mailserver, username and password read from the config file are the same as defined in the ASP.NET configuration tool. These mails are delivered successfully.