Reenable email tests

[tobiasdiez]

Disabled in #2783 since the provider for temporary email bag is down. Alternative is maybe https://mailsac.com.

[a-y-a-n-das]

@tobiasdiez I'm picking up this one...

[a-y-a-n-das]

@tobiasdiez Mailsac by default gives subject, date, attachment links, etc. But in order to get the body as plain text and html 2 more api calls will be needed, as they are different endpoints. Right now, in the tests, only the subject is used, so would you like me to include the body in the response too, or leave it out?

[a-y-a-n-das]

The current implementation returns along with plain text body.