The only option we have right now of seeing the Preheader text is when creating a new campaign. We've run into some issues when reusing a previous campaign and changing the Preheader text has been overlooked. It would be nice to be able to see the Preheader text in the preview screen and test emails... Right now you can't see it. You can't even see it when getting ready to send the campaign. You see all of your email info when getting ready to send... Subject Line, List, To, From, etc... but no Preheader text.
We recently sent out a large campaign that three different people proofed, but failed to catch an incorrect Preheader text because it doesn't appear when sending a test. The only time you see it or enter it is on the actual edit page, but it's easy to miss.
Please add the Preheader text to the Preview and/or Test emails. Would be nice to see it in the summary as well before you send your campaign. Thanks!