[bug-mailutils] Re: POP3d enhancements(EXPIRE)

[Sergey Poznyakoff]

Hi,

Some thoughts/questions that I have after testing EXPIRE stuff:

I guess that the actual removal of messages must be done by
pop3d itself, not by an external script as we supposed at the
beginning. There are several reasons for that:

1) This is the only way to implement EXPIRE 0.

2) Setup consistency. Sysadmin will not be required to remember
to fix up his cron scripts each time he updates the --expire option
to pop3d. Otherwise, I am sure that the most frequent error will be:
'start pop3d --expire N and forget to set up the cron job'.

3) Running a cron job that will remove expired messages from
*all users mailboxes* on a server with ~10000 users 
means a considerable strain for that server. Removing messages
asynchronously, before closing pop3 session is more preferable
in this context.

Second thought: currently X-Expire-Timestamp is set on each retrieved
message. This means that a user can effectively disable the imposed
expiration policy by simply retrieving messages each time he
opens a pop3 session. I'd propose to set X-Expire-Timestamp 
only on the very first RETR, i.e.:

void
pop3d_mark_retr (attribute_t attr)
{
  if (!pop3d_is_retr (attr)
    attribute_set_userflag (attr, POP3_ATTRIBUTE_RETR);
}

Third thought: shouldn't a message be marked upon executing TOP as well?

Comments, opinions?

Regards,
Sergey