You can configure Piwik to use GMAIL as the mailserver. To do so, login as Super User, go to Settings > General Settings, and configure the form as follows:
- Use SMTP server for e-mail: YES
- SMTP server address: smtp.gmail.com
- Authentication method for SMTP: Login
- SMTP username: your gmail username
- SMTP password: your gmail password
- SMTP encryption: SSL
All Piwik emails (Scheduled PDF Reports, Password reset confirmation, etc.) will now be sent using Gmail servers.