Redmine

Hi,

Recently i finished to install Redmine in a VM, and i have problem to send or receive emails.
Please see below my installation details;

Environment:
Redmine version 2.4.0.stable
Ruby version 2.1.1-p76 (2014-02-24) [x86_64-linux]
Rails version 3.2.15
Environment production
Database adapter Mysql2
SCM:
Filesystem
Redmine plugins:
no plugin installed

GEMS:
actionmailer (3.2.15)
actionpack (3.2.15)
activemodel (3.2.15)
activerecord (3.2.15)
activeresource (3.2.15)
activesupport (3.2.15)
arel (3.0.3)
bigdecimal (1.2.4)
builder (3.0.0)
bundle (0.0.1)
bundler (1.6.2)
coderay (1.1.0)
daemon_controller (1.2.0)
erubis (2.7.0)
hike (1.2.3)
i18n (0.6.9)
io-console (0.4.2)
journey (1.0.4)
jquery-rails (2.0.3)
json (1.8.1)
mail (2.5.4)
mime-types (1.25.1)
minitest (4.7.5)
multi_json (1.9.2)
mysql2 (0.3.15)
net-ldap (0.3.1)
passenger (4.0.41)
polyglot (0.3.4)
psych (2.0.3)
rack (1.5.2, 1.4.5)
rack-cache (1.2)
rack-openid (1.4.2)
rack-ssl (1.3.4)
rack-test (0.6.2)
rails (3.2.15)
railties (3.2.15)
rake (10.2.2, 10.1.0)
rdoc (4.1.0, 3.12.2)
rmagick (2.13.2)
ruby-openid (2.3.0)
sprockets (2.2.2)
test-unit (2.1.1.0)
thor (0.19.1)
tilt (1.4.1)
treetop (1.4.15)
tzinfo (0.3.39)
yard (0.8.7.4)

1. default configuration options for all environments
   default: # Outgoing emails configuration (see examples above)
   email_delivery:
   delivery_method: :smtp
   smtp_settings:
   tls: false
   address: "mail.xxxxx.com"
   port: '25'
   domain: xxx.com
   authentication: :login
   user_name: "xxxxxx@xxxx"
   password: "pass"
   enable_starttls_auto: false

Please could you advise on a method to us SMTP to send emails.

Thanks,
RDE