I suggest you use the KDETools PST to MBOX Converter software, which can convert the PST file to MBOX format without any error. This software extracts more than 20 email client applications, such as Entourage, Spicebird and many other email clients. The efficient PST to MBOX converter allows the user to select single and multiple files with a batch conversion. there is no file size limitation for converting PST to MBOX.
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The user can use a professional PST to MBOX converter software that provides complete data security and extracts complete information from the large PST file and then exports the recovered data Inbox, subfolders, outbox, sent items, deleted items, folders and etc. unique feature like batch conversion, split feature, message filtering and more. Visit:- https://www.dailysoft.org/pst-file-converter.html