An organisation is using Active Directory Domain Services and Office 365 but with no synchronisation so there are a large number of discrepancies between the user accounts (different spellings of names, outdated job titles, wrong UPNs, etc).
The organisation is planning to migrate to a new AD DS, keep the same Office 365, and use synchronisation via Azure AD Connect (read: it's important that the user accounts are correct in the new AD domain).
I have exported the AD and AAD / O365 user accounts to CSVs and reconciled the discrepancies so now I need to import the CSV into AD but the semicolon-delimited proxyAddresses are proving to be a problem because it's importing the data as one value, rather than multiple.
I couldn't find a suitable resolution online, hence this post.