Setting up a gmail account with vacation-responder
1. Click in your Gmail Account on the wheel (1) and then choose Settings (2)
2. Make sure to be in the Tab 'General' scroll down to Vacation responder then set it un on 'Vacation responder on' fill in subject and content
3. BEFORE YOU LEAVE make sure to scroll to the end and save your changes
In this 'Automated-Vacation-Response' you can fill in the Content (Like Resolution to a common problem of that specified Niche) in that way you can tell people (in forums or wherever) to send you an email to yourmail@gmail.com to send them the 'needed info / valuable content' back!
I forgot to mention in that same page, Settings, General (tab) scroll up again to find
Create contacts for auto-complete and set it on to ...add them to Other Contacts... to make sure you'll be able to export the contacts one day, when you wanna import it to a paid Auto-Responder-Service. (See picture below)
Also you maybe wanna set up a signature to make it look more professional & have the chance that they check you up on your other pages (Website, Social-Sites)
Put a mailto: link in your ad/email ad and ask they click the link to receive more info.
Using standard link formatting, add email link "mailto:name@yourdomain dot com?subject=Keyword You Selected"