. Net (C #): Do not use SMTP port 25 to check the permission for sending emails

When you do not use the SMTP port 25 to send an email, some low-Permission execution environments may throw an exception. You 'd better check the permissions before performing the operation.

 

SMTP has the following permissions in. Net: smtppermission type (and declarative smtppermissionattribute attributes, all of which are in the system. net. Mail namespace ). Its access attribute controls the permission content. Smtpaccess enumeration. There are three values: none (none), connect (default port 25 for connection), and connecttounrestrictedport (any port for connection ).

 

The following is a simple console code to check SMTP permissions:

// + Using system. Security;

// + Using system. net. mail;

Static void main (string [] ARGs)

{

VaR smtppermission = new smtppermission (smtpaccess. Connect );

If (isgranted (smtppermission ))

{

Console. writeline ("allow SMTP port 25 ");

 

VaR smtppermission2 = new smtppermission (smtpaccess. connecttounrestrictedport );

If (isgranted (smtppermission2 ))

Console. writeline ("allow SMTP for any port ");

}

}

 

// Determine the permission set of the current application domain

Static bool isgranted (ipermission per)

{

VaR pset = new permissionset (permissionstate. None );

Pset. addpermission (PER );

Return pset. issubsetof (appdomain. currentdomain. permissionset );

}