Since Postbox is based on Mozilla code, you can search the popular MozillaZine forums to see if any questions are similar to the ones that you have.
Try searching Google, as it is very likely that other people have posted similar questions/answers to the web, particularly for issues that relate to POP or IMAP protocol issues that are common to all email clients.
Work with your ISP, Web Hosting Company, or IT Administrator to identify issues that you may be experiencing in Postbox that are common to all email clients.
Note: While we read each and every request that comes in, we may not be able to respond to every inquiry. We appreciate each and every submission, but please know that Postbox works closely with a very large number of early access customers to identify issues, and at this time we are no longer accepting new applicants into this program.
Postbox is aggressively priced at $9.95, and while your purchase includes complimentary self-help support resources, it does not include one-on-one support. However, we do offer a Pay-Per-Incident Support option for $29.95, but first we recommend that you utilize the support offerings that you may have access to you through your ISP, Web Hosting Company, or IT Administrator.