When this happens, it is likely that the user has an alias, i.e. another email account that forwards the messages to his/her main email address. So they believe that the message was sent to the address associated with the mailbox that they are checking, but the message was actually sent to another email address, which redirects there.
For example, there might be sales@companyName.com and marketing@companyName.com that are an alias of john.smith@companyName.com (
all fictitious addresses).
In all of these cases, they can simply use the unsubscribe link in the footer of each message they receive (in case it is more than one copy of the same message): the unsubscribe link will allow them to unsubscribe that very recipient.
There is a rare scenario in which a message is received, but then the email address to which it was sent cannot be found in the system (and therefore you cannot unsubscribe it, or review the subscription status): it's when a message is sent, and then one or more of the email addresses to which it was sent are deleted from the system. Again, this is a rare scenario. This is one of the reasons why addresses should not be deleted from a list, but rather simply moved to the "Unsubscribed" group.
Article ID: 482, Created On: 11/11/2011, Modified: 11/11/2011