F5 load Balanced Archive Manager web servers separate from Archive Manager services server.
Website Published outside using SSL certificate.
PST taken out using search exporter when mounted in Outlook cannot open Attachments which are limited to 1KB irrespective of the original Size.
Attachments open fine from the Website.
HTTP to HTTPS redirection from the F5.
Potentially the redirection doesn't work for URL <http://Archivemanager> URL/DefaultInstance which is what is used when using search exporter when it extracts attachments.
1:) Created Host entry file:
IP address of one the webserver URL for Archive Manager
2:) Added Host Header value on Port 80 and Archive Manager URL.