c# - Seding email via WPF make app shutdown -

when try send email on computer enviroment(visual studio 2015) fine when copied computer(vmware virtual machine) , try run shutdown, here main code:

    try     {         smtpclient client = new smtpclient();         client.port = 587;         client.host = "smtp.gmail.com";         client.enablessl = true;         client.timeout = 10000;         client.deliverymethod = smtpdeliverymethod.network;         client.usedefaultcredentials = false;         client.credentials = new system.net.networkcredential("bazymysql@gmail.com", "xyz");          mailmessage mm = new mailmessage("donotreply@domain.com", "bazymysql@gmail.com", "przechwycony ciag znakow", tresc.text);         mm.bodyencoding = utf8encoding.utf8;         mm.deliverynotificationoptions = deliverynotificationoptions.onfailure;          client.send(mm);     }     catch (smtpexception ex)     {         messagebox.show(ex.message);     } 

what i've tried:

• copy system.net dll
• developing 86x 64x
• run admin

maybe can try following

try {     smtpclient client = new smtpclient();     client.port = 587;     client.host = "smtp.gmail.com";     client.enablessl = true;     client.timeout = 10000;     client.deliverymethod = smtpdeliverymethod.network;     client.usedefaultcredentials = false;     client.credentials = new system.net.networkcredential("bazymysql@gmail.com", "xyz");      mailmessage mm = new mailmessage("donotreply@domain.com", "bazymysql@gmail.com", "przechwycony ciag znakow", tresc.text);     mm.bodyencoding = utf8encoding.utf8;     mm.deliverynotificationoptions = deliverynotificationoptions.onfailure;     thread sendmailthread = new thread(()=>{         client.send(mm); //this ensure sending happens on second thread , not crash main thread.     });     sendmailthread.start(); } catch (smtpexception ex) {     messagebox.show(ex.message); }