IIRC there's usually an email and they also usually appear in the offers in the corner though I don't recall seeing them this time when I accepted mine at the beginning of the year.
The preapproved offers are done each quarter like the FICO NG2 score updates and are probably based on the score/pull. They'll mention specific products and amounts. Anything else is just marketing.
Don't overlook prior discussions as a resource as well.
