Eudora got tired, server time out regarding big mail?
In this case you may increase timeout Max 99999 seconds of 300 seconds from the Eudora configuration.

-Click Tools then Option, select Advanced Network and put in the Network timeout after 99999 seconds. If the big mail size is more than 5 MB you should delete it through telnet from the server yourself after viewing the top page. Telnet commands are given below: To enter the mail server: Click Start-click Run-type for BOL telnet mail.bol-online.com 110 or for Dhaka.net telnet mail.Dhaka.net 110 click OK. One black screen will appear where you will type user "your user name" press enter. Type pass "type the login password" press enter. Type list to see the total mail and size. Press enter retr x to see the specific mail where the x=no. of that mail. Press top x 10 to see x mail top 10 line where x=no of the mail) press dele x to delete the specific mail. Press enter quit to close the terminal screen. Press enter.