why does an original email I've forwarded on disappear and can only be found in the email I forwarded it to? This has never ever happened before

Hey Juanita279,

We'd be happy to help out. Sounds like you're not seeing your forwarded email in your inbox and only showing in your sent mail folder.

You can certainly move the forwarded email back to your inbox if you'd like to, however this behavior could be dependent on your email service provider. The best way to find out though for certain is by testing on the webmail. If you forward an email on your webmail, do you notice the same behavior? If so, contact your email service provider for more help from here. If not, then perhaps there's something going on in the Mail app settings that we can take a further look into.

For more info on forwarding emails in Mail on Mac, check out: Reply to or forward emails in Mail on Mac - Apple Support

We hope this information helps out with isolating things further.

Take care!