how can I delete a single email from all my apple devices at once

Hello Bree,

Yes it is possible however it is not entirely in control of your iPhone. The email service provider has a lot to do with it. Most IMAP type email accounts synchronize across all devices that log into them. Most POP email accounts depend on individual devices and status. Then there is the Microsoft based Exchange email accounts that accomplish the task as well (Outlook.com, Hotmail.com etc). In short the functionality that you seek depends on the email account service provider.

Axel F.

If you have the same email account on all devices, with the same username and password, and the account is using the IMAP email protocol (most do these days), it will happen automatically on all devices. You need to do nothing.