Reduce number of links in signup e-mail

Summary

Reduce the number of links in the welcome signup e-mail, to prevent it being flagged as spam.

Description

What is the current behavior?

Users in free.fr and laposte.net are not able to register to an e.email account. Mails from welcome are rejected as spam.

What is the improved behavior?

• Only 2/3 links in the signup e-mail (all languages, text and HTML versions).
• The non-essential links should be replaced with a single mention of https://e.foundation/get-started/
• Invitation e-mails are delivered to free.fr mail boxes.

What does it bring?

It lets users sign up for our service.