I would rather see this as a supported feature within Flow / SharePoint Online instead of a (heavily priced 3rd party tool.
Converting to PDF is an A tier functionality that is currently missing. Seems to me a 3rd party tool should not be necessary. Sorry, but it's true, Muhimbi.
I appreciate that - like with most third party software - it would be great for Microsoft to incude it in the box at no additional fee, but it is impossible to please everyone.
Until then - and while we work with Microsoft's Flow team to include our software in the list of Flow out-of-the-box services - you can add our PDF Conversion, Merging, Watermarking, Securing and OCR facilities to Flow and PowerApps as described at https://support.muhimbi.com/hc/en-us/articles/115002915647.
If you decide to use our solution, I am keen to hear about your experiences so let me know (via support@muhimbi.com) how you get on.
With regards to the actual PDF conversion (of MSG files as wel as many other formats), I am happy to announce that support for PDF Conversion, Merging, Watermarking, Securing and OCR is now available in Flow. For details see https://support.muhimbi.com/hc/en-us/articles/115002915647
I am keen to hear about your experiences so let me know (either in this forum, or by emailing support@muhimbi.com) how you get on.
You can now convert any documents stored in Onedrive For business to a PDF. Read more about this new feature here: https://flow.microsoft.com/blog/all-must-approve-and-onedrive/