It isn't *architectually* offensive for an expunge to be implicitly performed as a result of logging out. In fact, that is how POP works. Nothing in the IMAP standard prohibits a server from doing this.
However, the world has evolved in a way that many users would be quite unhappy if an expunge is ever implicitly performed by a server, even at LOGOUT time. Most users want client control over expunging.
I don't know of any server which offers this as a feature. Thus, you would have to implement it yourself.
The simplest thing, if you are using UW imapd (as you seem to be), would be to change the mail_close() call in the LOGOUT handling code, e.g. change:
else if (!strcmp (cmd,"LOGOUT")) {
if (arg) response = badarg;
else { /* time to say farewell */
server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
if (lastsel) fs_give ((void **) &lastsel);
if (state == OPEN) stream = mail_close (stream);
to something like
else if (!strcmp (cmd,"LOGOUT")) {
if (arg) response = badarg;
else { /* time to say farewell */
server_init (NIL,NIL,NIL,SIG_IGN,SIG_IGN,SIG_IGN,SIG_IGN);
if (lastsel) fs_give ((void **) &lastsel);
/* auto-expunge at LOGOUT time */
if (state == OPEN) stream = mail_close_full (stream,CL_EXPUNGE);
I'm of two minds on this question. I don't think that a user should delete a message if he is unwilling to face the possibility of an expunge happening. But I also understand why users may want to logout without expunging.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.
