We edited an email template but didn't know we had to update the metadescription / preview text, so we got something like this:
Subject: Our webinar is tomorrow!
Preview text: Our webinar is in one week, so don't be...
I've attached a screenshot of the problem.
I can't seem to find the space to edit this anywhere in Marketo.
Also, our emails are stored in marketing activities, not in the design studio.
How do we fix this?
The preview text comes from the very first line of the email.
Usually, it's better to set this as an editable zone in the template, so that you can change it for each email, at the very top of the email, together with the view as web page.
The "preview text" is called a "preheader" and there is a relevant thread here:
Regarding where Email assets live in Marketo, they can live in either Marketing Activities or Design Studio. Both are accessible from any Marketo Smart Campaign, regardless of where you created them. Also, you will see a view of all emails in your entire subscription if you go to Design Studio and click Emails.
I have a recommendation to make here:
-Make a business decision and stick to it.
It gets very hard for Marketo Users to find things when they are in different places, specially when it is a busy instance with multiple users.
Governance and documentation plays a very important role.
It could also be coming from your plain text version (make sure you update to match your HTML) or if you have an image with Alt text before your text. As Gregoire mentioned, it's best to make it editable zone in your email template.
With the editor v2, this is no longer needed. There is a built-in feature that makes it straightforward.