There is a mailinglist for Flask hosted on librelist you can use for both user requests and development discussions.
To subscribe, send a mail to firstname.lastname@example.org and reply to the confirmation mail. Make sure to check your Spam folder, just in case. To unsubscribe again, send a mail to email@example.com and reply to the confirmation mail.
The mailinglist archive is synched every hour. Go there to read up old discussions grouped by thread.