First of all, I am quite irritated that there is no contact address to send a regular email to... You are an internet company that offers a web email service, and it's impossible to email you? Seriously?
Now, regarding my original issue:
In general, receiving ads on my Gmail page is perfectly acceptable. You offer good products for free and it is legitimate that you sell ad space to generate revenues.
However, I have been very surprised just now to see an ad for the clothing store 'Thor Steinar'. In case you are not familiar with the company, please consider the following quote from the Guardian newspaper:
"Thor Steinar, which markets itself as an outdoor clothing company and has at least 12 stores in Germany, has become a popular label among neo-Nazis. Clothing from the label is banned from being worn in the German Bundestag."
Certainly, I can simply ignore the ad. But as a customer I do wonder whether you have defined criteria as a company, for which potential partners you advertise or not? I mean, you would not advertise for any client, would you? In my opinion you can and should forego revenue from partners who have based their business on hatred.
Your company principles state that: "You can make money without doing evil." You can. Your business partner cannot.