For anyone else that requires that same answer:
@tigeravatar spotted the mistake and is correct with the following: (No quotes around Me.lbSend.List(i))
For i = 0 To Me.lbSend.ListCount - 1
Set strEmail = ws.Range("A:A").Find(What:=Me.lbSend.List(i), LookAt:=xlWhole, MatchCase:=False, SearchOrder:=xlByRows, SearchDirection:=xlPrevious)
strTo = strTo & ";" & strEmail.Offset(0,1).Value
Next i