Unable to send email through SMTP

Hello

On my vps I can't send email through smtp from a Codeigniter website. I can receive and send emails from email client like thunberbird, from roundcube installed on the vps and from my localhost using smtp credentials to connect to the vps. Testing from online website I get this errors from the email debugger:

Code:

220 server-ip ESMTP Postfix

hello: 250-server-ip
250-PIPELINING
250-SIZE 10240000
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN

starttls: 220 2.0.0 Ready to start TLS

hello: 
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�l�<DC�J���!��UI����q8��jɲ����=��Z��Z� I�2�p�w��|M�ވS�V|^��{����

The following SMTP error was encountered: 
M
IA������[�[P���:*ǹ�L�OV�l4���_��怅��Des�3�b���d�V��z�z

`D��C�j��<����y���v�ت�D���V�dV��d.�?v���.ɐ��
栴��S)� Oc�:�)j���� �x�F!��u�x��@�{��e}�b�W��Ps�P?}��^�Yv�(fP����� M�9�������d��Ш3��.�h��ٴ��Њ%�w��G�B��̛�
�l�<DC�J���!��UI����q8��jɲ����=��Z��Z� I�2�p�w��|M�ވS�V|^��{����
Unable to send data: AUTH LOGIN
Failed to send AUTH LOGIN command. Error:
Unable to send data: MAIL FROM:

from:

The following SMTP error was encountered:
Unable to send data: RCPT TO:

to:

The following SMTP error was encountered:
Unable to send data: DATA

data:

The following SMTP error was encountered:
Unable to send email using PHP SMTP. Your server might not be configured to send mail using this method.

This is the output of mail.log

Code:

May 22 00:50:55 ns334612 postfix/smtpd[9796]: connect from server-ip
May 22 00:50:55 ns334612 postfix/smtpd[9796]: SSL_accept error from server-ip: 0
May 22 00:50:55 ns334612 postfix/smtpd[9796]: warning: TLS library problem: error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca:s3_pkt.c:1262:SSL alert number 48:
May 22 00:50:55 ns334612 postfix/smtpd[9796]: lost connection after STARTTLS from server-ip
May 22 00:50:55 ns334612 postfix/smtpd[9796]: disconnect from server-ip

I'm using codeigniter 2.2.

Hope some of you can help me.

A quick google of that TLS error message found this:

Should you get a warning message in your /var/log/mail.log that reads "warning: TLS library problem: 24125:error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca3_pkt.c:1256:SSL alert number 48:" then you are using a self-signed certificate and the email application refused the certificate. In this case the users need to add an exception so the certificate gets trusted.