Whether or not your audience will receive a "confirmation email" first (in which they'll have to click on the link to activate their subscription) depends on your autoresponders' settings.
In other words, you can control whether it's set at single or double opt-in by checking your autoresponders' settings (that's happening outside of ConnectLeads).
Please note there are some exceptions:
When you are using Aweber, you'll have to contact their support desk to manually disable double opt-in for your account. Because the emails are being from ConnectLeads into Aweber using their API, they automatically turn on "double opt-in" - regardless of the settings in your account.
In order to enable single opt-in for Aweber, you'll need to contact Awebers' support desk and ask for approval to get emails added using the API with double opt-in turned off.
To disable double opt-in confirmation message in GetResponse, locate the field labeled your current campaign in the upper right corner. Click the down arrow to select a campaign and click the gear icon to the right of the campaign name.
In the Permission tab, uncheck boxes under Enable confirmed opt-in section to disable double opt-in for email and web form subscriptions. If you leave the boxes checked the confirmation messages will be sent. Import subscriptions are set by default to single opt-in (no confirmation message is sent).