Identify the most common Claws Mail persistence configurations

Originally created by @intrigeri on #9494 (Redmine)

Set up various kinds of email accounts and local email folders in Claws Mail, and identify the most common configurations. Our doc about Claws Mail, including external doc we might be linking to, will be the starting point. But there may be other common configurations that we might want to support migrating away from.

Parent Task: #7773 (closed)

Related issues

Blocks #9495 (closed)
Blocks #9496 (closed)

Edited May 15, 2020 by intrigeri

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