iCloud.com - This message cannot be sent at this time. Please try again later

Since the recent IOS 15 upgrade/implementation I have been having issues with sending emails directly from iCloud.com. I have checked my email settings and I prefer to send emails from one of my alias addresses. When I attempt to send an email from this alias I receive the message 'This message cannot be sent at this time. Please try again later.' I also see that when drafting the email it states that it could not save a Draft.

When I then send an email using my primary address it works and sends with success. This is quite frustrating as I also had similar problems with my email after upgrading to IOS 15. I hope somebody in the community is able to provide some help with this matter.

Thank you in advance.