Can anyone help me set up out of office using Gmail?

[#1]

Hi,
I have Gmail configured to collect my mail from PlusNet using POP3 and I was hoping to be able to turn on the vacation message feature on Gmail - in fact someone else's post suggested this worked.
However, it only seems to reply if the message is sent direct to my gmail address, not when it is colected from Plusnet by POP3
I considered using a redirect on my PlusNet account but don't understand it - it won't let me select my plus net address as the redirect address "The redirect can't be the same as a mailbox you currently have on your account. " so does that mean I cannot redirect my main account? Am I being thick?? Even if I can make this work, will it just respond to my own address from Gmail or to the original sender?
Please help fast - I leave in two hours.
Cheers

[#2]

You can't have a redirect *and* a mailbox in the same name. If you want to change the address to a redirect you need to delete the mailbox first - but make sure you've a) specified another default mailbox first and b) that you've collected all the email from it, as otherwise you'll lose that when it's deleted.
Hope that helps,