You can send emails from a dedicated mailbox for your firm (e.g. info@yourdomain.com), by editing your personal settings.
1. Click your username in the top left corner.
2. Click Personal settings.
3. Scroll down to Send email from dedicated mailbox and toggle Yes
4. Click Save.
Now, all emails that you send and receive will come from your firm's general email address (e.g. info@yourdomain.com).