Secure connection in sending an email with WFA - winforms

Question

I'm using this function:
void SendEmail(String ^ sendTo, String ^ sendFrom, String ^ subject, String ^ body, bool enableSsl, char* user_login, char* user_pass)
{
SmtpClient^ client = gcnew SmtpClient();
MailMessage^ msg = gcnew MailMessage();
String ^ user = gcnew String(user_login);
String ^ pass = gcnew String(user_pass);
System::Net::NetworkCredential^ smtpCreds = gcnew System::Net::NetworkCredential(user, pass);
client->Host = "smtp.gmail.com";
client->Port = 587;
client->Credentials = smtpCreds;
client->EnableSsl = enableSsl;
MailAddress^ to = gcnew MailAddress(sendTo);
MailAddress^ from = gcnew MailAddress(sendFrom);
msg->Subject = subject;
msg->Body = body;
msg->From = from;
msg->To->Add(to);
client->Send(msg);
}
for send email. I have problem with 9th line - if I set static string like this:
System::Net::NetworkCredential^ smtpCreds = gcnew System::Net::NetworkCredential("adress#gmail.com", "my_password");
it's ok - mail will be send, but when i'm trying using my variable from other function application crashed with:
An unhandled exception of type 'System.Net.Mail.SmtpException'
occurred in System.dll
Additional information: The SMTP server requires a secure connection
or the client was not authenticated. The server response was: 5.5.1
Authentication Required. Learn more at
PS. Yep, SSL is enable.
I have login and password from file:
char * getAccountData(int marker, int lb_kont)
{
char wyjscie[256], login[256], password[256];
char * korektor = "||";
char * schowek;
string zawartosc_pliku;
ifstream NowyPlik;
NowyPlik.open("C:\\account.db");
for(int a =1; a<=lb_kont; a++)
{
getline(NowyPlik, zawartosc_pliku);
strncpy(wyjscie, zawartosc_pliku.c_str(), 128);
schowek = strtok( wyjscie, korektor );
strcpy(login, schowek);
schowek = strtok( NULL, korektor );
strcpy(password, schowek);
}
NowyPlik.close();
if(marker == 1)
return login;
if(marker == 2)
return password;
}
and for function which send mail i've set getAccountData(1,lb_kont) and getAccountData(2,lb_kont) as char* user_login, char* user_pass. Next i change char * to String (6th and 7th line in my first post).