If you face any issues importing Outlook OST to Thunderbird format and searching for the best software then you can use the eSoftTools OST to PST Converter tool. This tool gives accurate results. It’s 100% tested from anti-virus and online scanners. It can import all data of mailbox like emails, sent-items, deleted-items, drafts, outbox contacts, inbox, calendars, notes (To, Bcc, Cc, Subject, From, Object, Date, and Time) Into a newly created Outlook PST file. It can convert OST files into various formats like PST, EML, EMLX, HTML, Gmail. Office 365, MBOX, Vcard, and many more.
Know More:- Import Outlook OST to Thunderbird