Error: "Zend Mail Protocol Exception: is unsupported SSL type"
Solution: Comment out the email.secure option in $SIMPLE_INVOICES_ROOT/config/config.ini (see example below)

Error 2: Authentication Unsuccessful when trying to connect to Windows 2003 Exchange Server
Solution: Specify DOMAIN\username for format of SMTP email user. Where domain is your NetBIOS domain name and username is your windows login username.

email.host 	 		 = 10.11.12.13
email.smtp_auth			 = true
email.username			 = DOMAIN\username
email.password 			 = "mypassword"
email.smtpport			 = 25
; email.secure       	    	 = 
email.ack 			 = false