I have a web app "myapp.com" that users can use to set up their own websites. Our application is written in php and should be able to do the following:

• send mails to our own users "from: [email protected]"
• send mails from our clients to their clients "from: [email protected]"

We don't need to take care of incoming mails, just send out mails with the correct from and reply-to addresses.

We cannot make this work using Google Apps (limited to our own domain in the from-field) and we cannot make google apps or google apps domains for all our clients, so we are looking for another simple to manage and set up solution.

Does anyone have experience with this, please let me know! Thanks