Kirill Miazine put forth on 1/10/2010 11:28 AM:
Actually this is a wish of one customer, so I'm trying to figure out how much pain it will be do support such scenario.
One customer? Why is s/he requesting this? AFAIK, all POP clients default to "delete after download". And even if there is one that defaults to "leave a copy on server" I guarantee it has an option to "delete after download".
However, regardless, these aren't motivations. The only possible legitimate motivation for wanting this ability is that a customer is eating too much disk space. The answer to that is quotas. If you goal is that you just don't want to support POP anymore but only IMAP, then you send an announcement to your customer community that you will cease supporting POP on date xx/xx/xxxx and instructions for setting up an IMAP client can be found here: http://www.your-domain.tld/imap-instructions.
Something is amiss here. I fear you are not being truthful in your account of your motivations. There is no legitimate scenario for requesting this ability. Any possible motivation you could have for wanting this feature is better properly handled by options/methods already in existence.
-- Stan