Using a PST file, you can make a backup/export of your Outlook mail. All your mails will be saved in one (PST) file. It is the first step in the archiving process to prepare all your mails for long term archiving (PDF/A).

Step 1: Make a PST file of your Outlook folder(s).

Choose one of the export instructions below:

Step 2: Convert your PST files at to prepare them for long term storage (PDF/A). 

Convert your Outlook PST file to PDF/A

Learn more: Convert Outlook pst files to PDF, with attachments and folderstructure.