mport of Data into Mail under Mavericks

I use Mail 7.2 under Mavericks

Mail was pre-installed on my iMac. The Migration Assistant could not be used since the previous computer is a pre-intel PowerBook which did not have any corresponding tool. So the data had to be transferred manually. Mail provides for the option of “import”. I made a copy of the Address book resulting in a “abbu” file which I transferred to the iMac. and wanted to import in the brand-new iMac.

At this point, the iMac gave the following warning

“Are you sure that you want to replace all Contact data by substituting the contacts listed in “Contacts-DATE.abbu? if you click “Replace All”, your Contact data will be replaced by substitution of the data in the Contact archive.”you cannot Undo this process”

I fearthat to click Yes will delete my precious data from the previous computer. I do have Time Machine back-up copies but this will not help me to get the data into Contacts.

What do I do next?