In addition to company name, subject line, and preheader, Gmail now allows you to add more information to what your contacts can see before they open your email. These options are meant for the promotions tab.
You can edit the appearance of these items in the email design process.
While editing your email in the Email Studio, find the Content Tab on the left side, you will see a section labeled Email. This is where you will find options to edit these inbox promo options:
Inbox Logo
Displays a circular logo to the left of the subject and preheader. Optimal dimensions are 48x48px
Inbox Promo Image
Displays an image below the subject and preheader. Optimal dimensions are 358 x 138 or 3:9 aspect ratio.
Inbox Discount Offer
Displays highlighted text offer below the subject and preheader. e.g. “25% off!” or “free shipping!”
Inbox Discount Code
display a discount promo code below the subject line or preheader (only use this if you have a web store with promo code capability)
Inbox Discount Start –
Specify with the discount code becomes active.
Inbox Discount End –
Specify when the discount code expires.