When importing contact data from AutoResponse Plus (ARP3), there can sometimes be a problem with links that are specific to an ARP3 contact's subscription such as the unsubscribe, confirm, or next links.
To resolve this, access phpMyAdmin in your domain's hosting control panel (e.g., cPanel) and issue this SQL command on the database that holds your arpReach data:
UPDATE arpr_subscriptions
SET arpr_subscriptions.key=SUBSTRING(MD5(RAND()),1,6)
WHERE arpr_subscriptions.key=''
We advise this action for anyone who has imported contact data from ARP3.