When archiving an Outlook profile not all mails of the mailbox are being archived.
Posted by Lars Talaschus on 19 Jan 2016 16:32
When archiving an Outlook profile, not all mails of the mailbox are being archived; instead only messages of the last month or the last year are being archived.
Outlook can be configured to use the Exchange-Cache-Mode. Outlook then only has access to messages of a certain period in the mailbox.
When ActiveSync is used as protocol to connect to an Exchange Server, Outlook can be configured to synchronize only messages of the last month.
When archiving an Outlook profile, MailStore can only archive messages that can be accessed by Outlook directly.
Disable the Exchange-Cache-Mode or increase the timespan for messages that Outlook can access. Alternatively, archive directly from the original mailbox without having Outlook in between. MailStore is able to archive from Exchange servers, IMAP and POP3 mailboxes directly.
Further Reading: https://support.microsoft.com/en-us/kb/2733062