There is a problem where you send an email only to find later that is stuck in the outbox unsent and all you can do is to delete it. Its nothing to do with the general wifi and data conmections but is down to this app. I used to use a link to the yahoo site instead of this app which works much better, but in the end gave up after Yahoo kept nagging me to get the app every time I clicked on the link. Also have problems with moving mails to folders in the app. Give me desktop any time!