I use Thunderbird for my yahoo email account - and access through imap. I have two computers and an android phone that access the account via imap. Every couple of days one of the computers running Thunderbird starts downloading all the email from scratch. There are 60,000+ emails stored in the yahoo account and it takes a while for them all to get downloaded again. Is there some sync issue or message id issue that is being created by using the androif phone client that is messing up Thunderbird?