In this solution i try my best to explain how to get this achievement on the normal way.
I got the achievement in Season 19 and i did only a few of the side events every year. What counts are the messages from your team, the Twitter-like feed doesn't matter.
And now: How to get the 500 messages without wasting time.
You will need around 18~20 seasons to get all the career achievements (historic goals etc.). For some, this will be enough, but for others it wont be. I would suggest you do a few side events every season to get some more races. Also, winning accolades will mostly unlock new events (with new races).
Doing some side events will give you the 500 messages sooner or later, but to save time, here is a trick I figured out:
After every Qualifiying, back out to the career hub (or the calendar). Don't start the race from the Qualifiying! In the career hub, check your messages, you should now have a message from your team about your qualifiying performance. After you have read the message go to the race. After the race you should have a message from your team about your race performance. You now have 2 messages. Going to the race immediately after qualifiying will give you only 1 message about your race, not about the qualifiying.
NOTE: UnfurledEmu75 pointed out that you dont have to reed the messages (immediately).
So, always go back to the career hub after each:
Qualifiying,
Race (also go back out after Race 1 if the event has two Races)
You leave the qualifiying or race 1 after it ended by "Quit" > "Save results"
You will only get a message from your team in 9 out of 10 cases, so dont be surprised if you dont get a message.
I hope the guide is helpfull. English isn't my mother tongue, so maybe there are some language mistakes.