Each time I click the email icon in ACT to start an email message in Outlook, I get a box...

As far as I can tell, this is more an issue with Outlook than with Act! Basically, there are 2 potential causes for this issue. Either A) your Security settings in Outlook are set to "Always warn me about suspicious activity", in which case it will give this message no matter what program you use to access Outlook programattically. or B) Your Outlook Security Settings are just the default setting "Warn me about suspicious activity when my anitvirus software is inactive or out-of-date (recommended)", which means that it will only pop up that message if Windows thinks your Anti-Virus is off or out of date. So, if it's A), then you just go into the Trust Center Settings for Outlook and toggle it to the default option, or if it's B), you need to activate/update your Antivirus.