how to send email using iphone app

i am developing an app to send Email to the Users with Some text and imgaes but the Problem is when i am using Gmail it is sending Emails some time but some it is not, i am using port 587 for gmail and when i am using my official Email i am using my official relayhost and Port number they are correct but the mail is not sending , help me please ....

SKPSMTPMessage *test_smtp_message = [[SKPSMTPMessage alloc] init];

test_smtp_message.fromEmail = @"ramakrishna@gmail.com";

test_smtp_message.toEmail =@"ramakrishna@domain.com";

test_smtp_message.relayHost =@"mail.domain.com";

test_smtp_message.requiresAuth =1;

test_smtp_message.login =@"ramakrishna@gmail.com";

test_smtp_message.pass =@"test1234";

test_smtp_message.wantsSecure = 1; //

smtp.gmail.com doesn't work without TLS!

test_smtp_message.subject =@"User Registration Details";

and our port number is also write but still not working .........