Changing an email alias to an email redirect

[#1]

Hi
I would like to change an existing email alias (e.g. "xyz" ) on my Plusnet mailbox into a redirect to an external webmail for a period of time, so that any email sent to xyz@myusername is delivered to that webmail. When I've entered the required details on the relevant Manage My Mail pages I get a warning:

Quote

Please confirm that you want to replace alias "xyz" with redirect "xyz" Important: Once you've replaced this you won't be able to recover it.

What does it mean by

Quote

Once you've replaced this you won't be able to recover it.

? In a few months time, I will want to go back to receiving email addressed to xyz at my Plusnet mailbox. Will I be able to remove the redirect for xyz and recreate it as an alias at that time?
I hope I've made this clear.
Your advice would be appreciated.

[#2]

That message is very misleading - it's more appropriate to when a mailbox is deleted when all it's contents will be lost.
I've not had luck in the past when I attempted a direct change - safest would be to delete the alias first and then create the redirect.
There will be no issue with reversing the process when the time comes.