Convert portfolio to single pdf file

Hi, I have a portfolio of my email archive which I want to convert to a single pdf file. The way I'm doing it is by combining files and adding the portfolio file and then clicking combine, merge files into a single pdf, adding the portfolio and selecting single pdf file. This 'breaks up' the portfolio into its individual constituents which you can then combing into a single normal pdf file.

But there is a problem. In the portfolio the original date of the email is retained so you can sort the emails chronologically. However, when the portfolio is broken up the individual files are dated on the date the portfolio is created and so the new file is not sorted in the chronological send/receive order of the emails.

So my question is: how do I combine emails to a single pdf file in the chronological order of the emails?

Many thanks

Ps Since typing this message I've noticed that when printing all files in the portfolio it also doesn't print it in chronological order even though that's how they're sorted in the portfolio.