@BLUEFROG and @mdbraber - Thank you both for the suggestions
The reason I am trying screen captures is that the DT3 web clipper does not work at all on Outlook OWA. Due to either security or complexity of the site, the best I wind up with is a bookmark to the email but it will not download the actual email content.
Cleanshot X can create a screenshot, but its scrolling feature is not very good and often results in distortion of the email.
The reason I am not just importing them as .eml files is that I prefer webmail over local Apple Mail so I do not need to worry about syncing my laptop regularly. If I were to use Mac Mail on my laptop and I do not travel for a couple weeks, then it takes a while to bring Mac Mail up to date and if I do not do that from home, the bandwidth in a hotel may be unrealistic to get it back in sync.
I am forever trying to perfect the best way to import email - including this script which I use to import a full email including attachments via webmail The Ultimate Email Import Script or Mac Mail import when I am at a computer that has my full email synced to it.
But in the case of an email message with no file attachments, it would be nice to be able to clip a screenshot of the email from web to Devonthink.
I supposed I am obsessed with optimizing the workflow for email import to DT3 because I probably do this a couple dozen times every day.
In the end it seems that Outlook OWA does not “play nice” with regard to automation. Tricks that work on almost any other site do not work there.