#388 Error sending mail to contact groups

[TLTL]

Simple Groupware version: 0.745
Simple Groupware language: ptPT
PHP Version: 5.4.7
Database + Version: mysql 552
Server OS: Windows NT TLKI-PC 6.1 build 7601 (Windows 7 Home Premium Edition Service Pack 1) i586
Webserver: Apache/2.4.3 (Win32) OpenSSL/1.0.1c PHP/5.4.7
Webbrowser: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:20.0) Gecko/20100101 Firefox/20.0
APC cache usage: not installed
Disk usage: 375 GB / 931 GB

Hello,

I created 3 custom modules: email_ki, contactgroups_ki2 and contacts_ki2 and I always get the following error when I'm trying to send an email to a contact group previously created:

"Gatilho falhou trigger::sendmail Erro-Smtp data: Invalid response code received from server: 503 valid RCPT command must precede DATA"

I send you the modules files emails_ki.xml, contacts_ki2.xml and contactgroups_ki2.xml in attach.

Thank you for your help,

Best