mozilla thunderbird Keeps missing messages

[bluegrass1]

As the title states I use Mozilla thunderbird to keeps track of a few accounts ..
I keep logging into accounts and there is messages and items sold and not ever did I get the item sold or the payment received . anyone else having troubles ? Also what else is similar to thunderbird but more dependable .. Oh and I log into the email direct and bam there is the messages from a few days ago .. also even checked the spam folder on TB and nothing at all..