We moved to ProtonMail Business Workspace and forgot to verify the availability of that feature — I guess we took it for granted, coming from dedicated enterprise SMTP/IMAP servers. After experiencing communication chaos with our customers for about a month, we're already considering moving away from ProtonMail.
If only it were as easy to set the standard Reply-To header as it is to set a CC: that would help a bit while we wait for the "Send from Group Address" feature to be added.

This is the single most important thing prohibiting us from moving off Google Workspace at the moment. Without the ability for members of a group to respond as the group, we have problems with client trust who would otherwise receive emails from individual accounts rather than the general contact point.

As part of teamwork and the responsibility of representing the organization, the ability to send emails on behalf of the company is crucial. This functionality is crucial and essential for effective communication and avoiding fragmented correspondence that leads to information chaos.

I used Workspace for years, and routinely used send-as-group for things like supporting my adult son with his ADHD, and services shared by multiple family members (e.g. group addresses for each car registration in the family).