I came across 2 postings regarding this problem but both are over 5yrs old and deal with much older versions of TB. Further, like most forum discussions, the topic became tangential very quickly and both threads did not conclude with a usable solution. I hope this time will be different. As stated, each time TB starts up a new inbox-"x".msf is created. (eg. inbox.msf, inbox-1msf, inbox-2msf,... inbox-30.msf and etc...) and any older inboxes are ignored. This happens even when all defaults are observed. It's also worth noting that the "System Integration" pop-up dialog box appears every time TB is started, regardless of any previous option(s) selections. To simplify backup config and gain better control, TB's Profile directory structure is moved to %userprofile%. In this instant, after installing Windows 10 Pro onto a new SSD, TB's Profile directories was copied to the new %userprofle%. By redirecting the "Local Directory" to the appropriate existing email account directories prior to logging onto the email server, for each "newly" re-created email accounts in TB, it is possible to migrate all your email accounts from one machine to another without any loss or interruptions to your email accounts. After TB's 1st restart, "to apply the change" of the new "Local Directory" everything under that email account (inbox, trash, sent, Archives, other folders, and etc...) is migrated and fully accessible. BUT with every subsequential restart of TB, a new inbox-"x".msf is created in an incremental fashion and any older inbox-"x".msf is ignored. I had relied on this simple method of migration many times through the years and had no problems till now. After playing the setup "variation game" I am now convinced that these 2 problems lie within TB and not with my migration method. Please help. Thank you....