As I said, I don't know much about SpamAssassin. But quick search brought up Mail::SpamAssassin::Client which implements protocol for talking to spamd.

Note, the page for Mail::SpamAssassin says

If you wish to use a command-line filter tool, try the spamassassin or the spamd/spamc tools provided
So, I would believe, that these tools are good only when you have to use external commands, for example when you program not in perl, but in shell.

In general, to increase throughput, you should make processing of each message independent as much as possible, so that one message does not have to wait for another. That usually means, that each message handler should run either in separate process, or in separate thread. Using separate spamd is of help only because it internally uses multiple processes/threads to handle messages. But if you feed your messages one by one, then the benefit is lost. And opposite, if you handle your messages in separate processes/threads, it does not make sense to move spamassassin into separate process, because you just add extra overhead of communicating with that process.

In reply to Re^3: Help with setting up spamc by andal
in thread Help with setting up spamc by SteveTheTechie

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.