Can't send email

This error can appear when trying to send email from Email section or when user registers:

We're sorry, but something went wrong.
We've been notified about this issue and we'll take a look at it shortly.

• Check GUI log

Default settings

• SMTP Server: smtp.gmail.com
• Domain: localhost.localdomain
• Login: kolmitest
• Password: kolmitest99
• Batch Size: 50

Errors

Net::SMTPAuthenticationError (535 invalid user ID or password)

On both of these errors:

1. Check your SMTP server details
2. Try to use another SMTP server
3. Try default settings:

SMTP Server: smtp.gmail.com 
Domain: localhost.localdomain
Login: kolmitest
Password: kolmitest99

NameError (undefined local variable or method `xxxxxx' for #)

Do not add variables which are not from this list:

• <%= server_ip %>
• <%= device_type %>
• <%= device_username %>
• <%= device_password %>
• <%= login_url %>
• <%= login_username %>
• <%= login_password %>
• <%= username %>
• <%= first_name %>
• <%= last_name %>
• <%= full_name %>

Timeout::Error (execution expired) /usr/lib/ruby/1.8/timeout.rb:54:in `open'

Open port 25 to allow SMTP connection.