I would like to allow students to be able to block any mail from coming
into their own
account. So if Sally no longer want to receive mail
from acompany.com she can block it from
reaching her account but
Johnny can still receive it in his account. Since no accounts
have
shell access, this would have to be done through a web form.
So what Sally blocks
won't block Johnny, right? Because Sally may decide to block AOL.com and
Hotmail.com :-
)
My questions are:
Is this possible?
Almost anything is possible, it comes
down to time and money and how satisfied you are with the limitations of the
result. :-)
Has anyone done this successfully?
That I cannot say, although I would be surprised if
you were the first.
Can someone please point me in the right direction or even share
some sample code?
The easiest (theoretical, untested) way to do this would be to have two
plain text files in each user's $HOME, say $HOME/.procmail.blocked.domains and
$HOME/.procmail.blocked.senders
Your web form would ask if the new entry was a single
sender or an entire domain, and then append the info to the appropriate file.
You should
be easily able to find procmail code/recipes that will do this for you,
searching the
archives for fgrep and whitelist/blacklist should help.
Would this cause any
performance degradation on the system?
Sorry, I'm feeling a little extra playful
today, so I have to say this...
Everything, even 'cat', causes a performance
degradation. Whether that is noticable or cause for concern has much to do
with the specifics
of the situation.
Would appending one name to a file degrade performance? Not likely,
no.
Would having a user who has 5,892,274 domain names in their blocked file cause
a
problem? It might, especially if it exceeds LINEBUF.
For "normal" operations, I would
not expect a degradation of performance
TjL
ps -- Someone will undoubtably post an URL
to the site that describes why procmail really isn't the best tool for spam
fighting, to which
I agree. Strict punishment (i.e. burning off the fingertips of anyone who
spams or causes
spam to happen) might be the only way, but most of society isn't quite there
yet ;-)
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