Wanted to let all know a basic solution for importing Distribution Lists that worked very well for me in my setup. (With many kudos to chh and uxbod for their postings on this issue that greatly assisted :->) This may seem very base level info for some but in case this may help others.........

First created new DLs in Zimbra Admin Console
Next used Excel to insert and create fields in existing e-mail listing I had imported in form of:
addDistributionListMember My_Staff_List@myzimbraserver.com external_user@aol.com
and saved as MS Text .txt file.
Copied 'mylist.txt' to my Zimbra home directory and made sure rights for the file were set so Zimbra user had full rights to it. (Don't laugh, but forgot to do this the first time and then wondered why it did not work......)
Run at command line as Zimbra user:
zimbra@zimbra:/home/zimbra> zmprov adlm < mylist.txt
Worked super! I now have all of my DL lists in, they are are listed in the GAL for users and ready to go!. :->

Now a question......
In order to send out mail using the new Distribution Lists I needed to keep checked 'Can Receive Mail' in teh DL setup in the Admin Console. Does this mean that anybody out there on the internet can use these lists? That would be bad. I want these Distribution Lists only available to be used by internal Zimbra users. Any way to restrict that?