Redmine – how to configure email sending with postfix

I've installed postfix as my smtp server and it works fine, cuz I can send e-mails, for example by typing:

sendmail mail@mail.com

and e-mail is delivered corectly. But now I would like that redmine would send notifications to the users. That's my redmine installation info:

Environment:
Redmine version                2.5.2.stable
Ruby version                   1.9.3-p547 (2014-05-14) [x86_64-linux]
Rails version                  3.2.19
Environment                    production
Database adapter               Mysql2
SCM:
Subversion                     1.8.8
Git                            1.9.1
Filesystem                     
Redmine plugins:
no plugin installed

And the configuration.yml:

default:
# Outgoing emails configuration (see examples above)
email_delivery:
delivery_method: :sendmail
smtp_settings:
address: 127.0.0.1
port: 25
domain: dev.my-domain.org
authentication: :login
user_name: ""
password: ""

After changes of yml file I've restarted apache every time of course. But all the time I'm getting following error when trying to open notifications config page:

Email delivery is not configured, and notifications are disabled.

Configure your SMTP server in config/configuration.yml and restart
the application to enable them.

How to deal with it?