Nevermind...I was able to figure out using the link posted by Luis. Came with this SQL and it works.
WITH Ranked (AID, rnk, EmailID)
AS (SELECT AID,
ROW_NUMBER() OVER (PARTITION BY AID ORDER BY AID),
CAST (EmailID AS VARCHAR (8000))
FROM #TEST1),
AnchorRanked (AID, rnk, EmailID)
AS (SELECT AID,
rnk,
EmailID
FROM Ranked
WHERE rnk = 1),
RecurRanked (AID, rnk, EmailID)
AS (SELECT AID,
rnk,
EmailID
FROM AnchorRanked
UNION ALL
SELECT Ranked.AID,
Ranked.rnk,
RecurRanked.EmailID + '; ' + Ranked.EmailID
FROM Ranked
INNER JOIN
RecurRanked
ON Ranked.AID = RecurRanked.AID
AND Ranked.rnk = RecurRanked.rnk + 1)
SELECT AID AS AID,
MAX(EmailID) AS EmaiID
FROM RecurRanked
GROUP BY AID