Yahoo changed a number of things and you may see an error like host not found or EOF failure. Please do the following:
1. Remove the existing yahoo account, long-press the account on the accounts screen click delete
2. Yahoo has changed their approach a bit. First login to the yahoo mail account on any pc, then set it up in MailDroid this way:
1. Email/Password
2. Manual
3. IMAP
4.
Incoming:
Port: 993
Secure connection box should be checked
Outgoing:
Port: 465
Secure connection box should be checked