Don’t know if this post was originally in this Forum or being moved frm this Virtualization Forum.
Although 99% of Postfix questions probably belongs in te Apps Forum, this appears to be one of the rare exceptions.
According to the log entries you posted you appear to have a problem with the last snapshot you took (hopefully taken just before your updates).
Although I’m not a VirtualBox user, I assume the solution should be the same as other virt technologies, rollback to your system prior to the snapshot, boot and commence again.
HTH,
TSU