When you reply to a forwarded email, it should go out from your alias address rather than your real one. If that's not happening, work through these checks.
Is Can Reply enabled on your destination?
Go to Destinations and check whether Can Reply is toggled on for the destination you're replying from. If it's off, replies go out from your real address. Toggle it on.
Is the alias in Strict mode?
If the alias's permission mode is set to Strict, only the destination the alias is directly assigned to can reply through it. If you're replying from a different destination on your account, it will be blocked.
Check the alias's permission mode under its settings. Switch to Open if you want any destination with Can Reply enabled to be able to reply. See Alias permission mode.
Are you replying to the forwarded email?
The reply feature only works when replying to a forwarded message — not a new compose. AliasFleet uses headers in the forwarded email to know which alias to route the reply through. If you're composing a new email from scratch, it won't go through the alias.
Did you get a bounce notification?
If the reply was blocked, AliasFleet sends you a bounce email explaining why. That email also contains a one-click link to enable the relevant permission without going to settings. Check your inbox for it.
Still not working?
Contact support with the alias address and destination involved. Include when you tried to reply and what happened.