[exim] Should I block exim port?

Hi to everyone;

I liked too musch exim as my MTA...

But I have real problems, about spams... :-/

I activated my spamassassin for exim. Many spams are blocked with this
system however few of spams are not blocked. How can I solve this problem?
My server's port for exim(587) is directly open to world wide. Should I
close it? or how can I secure it for blocking all spam mails. I have one
more opened port also which is may not releated with this mail list but it
is closely the same issue. The other port is for imap(143), should I also
block it or how can I secure it. I thing that my questions are closely the
same "securing the mail server"...<;-)

Any help any suggestions will be glad...

sincerely... Have a nice life with opensource...

--
Tolun ARDAHANLI
Bilgisayar Muhendisi
E-posta:tolun.ardahanli@???<E-posta%3Atolun.ardahanli@???>
Icq:326600

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Tolun ARDAHANLI
Computer Engineer
E-mail:tolun.ardahanli@??? <E-mail%3Atolun.ardahanli@???>
Icq:326600