What is the difference between the three mail image storage options: attachment, Dropbox and FTP?
The Awesome Mails App provides you with multiple options for sending your mail:

1. Classic Attachment Option (simple, static email document)

Video demo for attachment option:
http://youtu.be/ahrInvvZ6Rk

2. Dropbox, requires Dropbox account, free at Dropbox.com (interactive email with support for web hyper links)

Video demo for Dropbox option:
http://youtu.be/OHxX3q8kOIk

3. FTP, recommended option if you have your own website (interactive email with support for web hyper links)

Video demo for FTP option:
http://youtu.be/4WqDTvC3-50

Both Dropbox as well as the FTP option support hyper links in email documents.

Some users find it's easier to set up the Dropbox option, all you have to do is press the link button to integrate Awesome Mails with your existing Dropbox account. (You may sign up for free at dropbox.com)

If you have a website with a FTP account, we recommend selecting the FTP option. This option allows the mail image to be uploaded to your own website server.

It's important to enter the correct FTP account information under FTP settings. Please make sure you enter a valid Website Base URL in order for the mail image to be rendered successfully.

Tips for setting up FTP option:

If you find the mail image has been uploaded successfully to the server, but the content in the email compose screen is blank, this means the Base Website URL may need to be adjusted. This URL is usually your website domain address (i.e. http://www.mywebsite.com )

If your FTP account does not point directly to the web publishing folder, the web folder name may need to be appended to the FTP server address as a suffix. (i.e. ftp.mywebsite.com/public_html/)