Anyone else run across authentication issues with gmail as smtp server?

I've setup my mail settings in AC as follows:

mailing type:SMTP
smtp host:smtp.gmail.com
SMTP port:587
SMTP authentication: yes
username:myusername@mydomain.com
Password:mypassword
seecuirty:tls

I've turned on debugging in config.php and found this error:

error - [User Error] <br /><strong>Uncaught Error</strong> of type [Swift_ConnectionException] with message [Authentication failed using username 'myusername@mydomain.com' and password '********************']<br /> 

@0 require_once() in /var/www/vhosts/mydomain.com/subdomains/projects/httpdocs/public/index.php on line 33<br /> 
@1 AngieApplication::handleHttpRequest() in /var/www/vhosts/mydomain.com/subdomains/projects/httpdocs/activecollab/init.php on line 86<br /> 
@2 execute_action() in /var/www/vhosts/mydomain.com/subdomains/projects/httpdocs/activecollab/angie/classes/application/AngieApplication.class.php on line 99<br /> 
@3 PageController::execute() in /var/www/vhosts/mydomain.com/subdomains/projects/httpdocs/activecollab/angie/functions/environment.php on line 92<br /> 
@4 Controller::execute() in /var/www/vhosts/mydomain.com/subdomains/projects/httpdocs/activecollab/angie/classes/controller/PageController.class.php on line 89<br />
 @5 SystemToolsController::test_email() in /var/www/vhosts/mydomain.com/subdomains/projects/httpdocs/activecollab/angie/classes/controller/Controller.class.php on line 81<br /> 
@6 ApplicationMailer::mailer() in /var/www/vhosts/signalfly.com/subdomains/projects/httpdocs/activecollab/application/modules/system/controllers/SystemToolsController.class.php on line 68<br /><br />

 (in /var/www/vhosts/mydomain.com/subdomains/projects/httpdocs/activecollab/angie/classes/swiftmailer/Swift/Errors.php on 99)

I know the username and password are correct and I've tired using smtp without tls or smtp authentication, but nothing works.

Please help!