I still have that email as well... to be precise, it says:
No annual fee on your Citi® / AAdvantage® American Express® card as long as your Citi® / AAdvantage® MasterCard® account remains open and the mileage cap is shared.
There are two footnotes:
The combined maximum number of AAdvantage® miles you can earn from purchases using your Citi® / AAdvantage® cards is 60,000 AAdvantage® miles per calendar year (recorded on your Jan.-Dec. billing statements). Any AAdvantage® bonus miles earned are excluded from this mileage cap.
AAdvantage Executive Platinum® members, AAdvantage Platinum® members, and AAdvantage Gold® members are also excluded from this limit. AAdvantage® miles are earned on purchases except returned goods and services, cash advances, convenience checks, transferred balances, credits, fees and finance charges.
... and ...
As of November 3, 2007, standard variable APR for purchases - 17.49%; standard variable APR for cash advances - 22.49%. However, if you default under any Card Agreement, Citi® may automatically increase the rate on balances (including promotional balances) to a variable default rate of 31.49%. The annual fee is $0 as long as your Citi® Gold / AAdvantage® World MasterCard® account remains open and the mileage cap is shared. Otherwise, you will be billed an annual membership fee of $50 for the Citi® / AAdvantage® American Express® card. Minimum finance charge - $.50. Foreign purchase transaction fee – 3.0% of purchase amount after its conversion into U.S. dollars. Cash advance fee – 3.0% of cash advance amount, $5 minimum. Balance transfer fee – 3.0% of balance transfer amount, minimum $5
Neither of the footnotes suggest there are special hoops to jump through to get the deal.