Had this same issue one week ago, (after 4 years trouble free) and Frontier C/S was able to get the new mail downloaded from client server to T-bird. This morning the last new mail came in about 4am and I daily receive about 10 by 8am. Yes there were 16 new messages on the server (webmail.frontier.com) but I couldn't fine the trigger to move them to T-bird. I did check the password save in T-bird, correct. Separate issue, starting last Nov. all new mail went to Trash instead of the inbox. Since I couldn't resolve this I worked around it daily. Thanks for help. Lyle