A user has multiple accounts and personalities in his settings.
If he sends out an email with an account/personality different to his default, then in the mail-header there is still
even if he explictely sets the return-adress in the account-settings. This is very annoying.
I attached a screenshot where you see the settings-page for an external account. When I send out an email from this accout the Return-Path is the adress set in "Primary Account"
The user wants to send mails from external accounts that leaves no trace about his primary account.