Using the above top secret URL you too can find out when you sent your first Gmail.
For me it is almost 10 years.
In that time Gmail has gone from my secondary email system, to a joint primary email system (shared with Microsoft Outlook), until today when it's now my only email system
It is certainly not perfect and does not have all the features (or complexity) of Outlook
However, I can look at or search through all my emails, from my computer, Chromebook, Desktop or even Smartphone
I can write beautifully formatted text and include graphics, attachments or links.
And if I'm not happy I can takeout my mail and startup elsewhere
Thanks Google, I look forward to the next 10 years.