Email forwarding to another domain not working

[alento]

How do you forward mail to external mail systems?

I have a few email addresses that I receive email for that I want to forward to external systems. Aliases works fine for forwarding to internal mail addresses and to some external systems (that don’t check or care about dkim). For those destinations that do care and where the sender has tied down the valid sender, the mail will bounce. What is needed is to forward the email (possibly as an attachment) from the relevant miab account. Could this be done, or is there code available that will do…

Please turn on SMTP authentication

I have a domain with about 20 aliases. These all forward to the individuals personal mail accounts. There is one account that when I email them, I get the mail bounced back as below; This is the mail system at host box.unitymail.co.uk. I’m sorry to have to inform you that your message could not be delivered to one or more recipients. It’s attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text …