I found out recently that a different team has been using the View in a webpage (VAWP) links for a website archive. The emails are "alerts" to a specific audience and the website archive is behind a secure login. We are required to keep a rolling 2 years of "alerts" in the archive. I found out we were doing this because now emails from 2019 (and one from 2020) are giving 404 errors.
I assume that utilizing this link isn't a best practice since from my own testing the VAWP links are dynamic. Of course Marketo only shows 6 months in the audit trail otherwise I was going to look up the emails to see if a draft had been created and approved over the previous version. In the archive one email from Jan 2020 has a broken link, and that campaign has an approved email with a draft.
I have two questions: 1) should we stop using the VAWP link and 2) any recommendations for storing emails in an archive other than PDF?
The VAWP content is always the content as of the moment you request the page — and of course, the personalized content for the user whose VAWP token you're using.
Either one of these characteristics can either be a minor problem or a huge problem, depending on how you use Marketo. In general storing the link, as opposed to the content at the link, is not advised.
And to your second question: AFAIK, there's is no easy way to create an offline archive of Marketo emails. We used grab the HTML code of the generated email and put it onto internal documentation pages, but the process is tedious. (Results can be very pretty though!).
I faintly remember some third party tools being discussed here, but I don't remember which ones. If - for instance - you were using Litmus to build your emails, you could certainly maintain your archive there.