SUBSCRIBE TO EMAILS & NEWSLETTERS:
In CONTACTS TAB > CONTACT NAME > PROFILE, you have a section called "Subscription Settings" where you can (un)subscribe your client or prospect to your newsletter and emails. Depending on the case, check "Yes" from "Client is subscribed to newsletter" and/or "Client is receiving emails" and click on "Save".
Important note: This only means that the contact will be eligible for being sent these types of communications. When sending the actual messages, you need to select the names of the specific contacts (emails) or the group they belong to (newsletters).
SUBSCRIBE TO AUTORESPONDERS:
In the case of autoresponders, below the "Subscription Settings", there is an "Autoresponders" list with all autoresponders (Opt-in, New Client and the custom autoresponders created in the COMMUNICATE module). Check the boxes in front the autoresponders you want the contacts to be subscribed to and click on "Save" to implement the changes. To the right of the autoresponders, you will then see the dates when the contact was subscribed.
In the PROFILE tab of the contact > section "Subscription Settings", choose "No" from "Client is subscribed to newsletter" and/or from "Client will receive emails" and click on "Save". To the right of the settings, you will see when the client was unsubscribed from newsletters and emails.
As for autoresponders, un-checked the boxes in front of the autoresponders you want the contact to be unsubscribed from and click on "Save".