How to save an email
Can't I just forward the email?
Short answer: No. Long answer: No, because when you forward the email, the email headers and contents of the emails are changed. This means that the original headers, which are very important when debugging deliverability, are lost.
Furthermore, the contents of the email will have been interpreted and changed by your email client. This means that the consultant won't be able to see the original email, but rather a version of it left in whatever state your email client deemed relevant.
Luckily, Gmail makes downloading a copy of an email very easy. Simply open the email and click the three dots in the top right corner. Then click "Download" and your browser should download a file to your downloads folder. The file has .eml (short for email) as its extension.
This also works if you're using Google Workspace.
Outlook is a bit more complicated. You can't download a copy of an email directly from the web interface, but you can do it from the desktop application.
Open the email in Outlook and click "File" in the top left corner. Then click "Save as" and choose "Outlook Message Format - Unicode" as the file type. Then click "Save" and your email should be saved to your downloads folder.
Sending the email
When you have a copy of the email on your machine, whether it is .eml og .msg format, you can simply attach that file to an email and send it.