I agree on the mechanism. A few more thoughts:

You can retrieve the first $N lines from a mail message from the POP3 server, with top. See Kill that Swen worm on your POP3 account! for example code.

You can probably read past the text part of the message and into the first lines from the attachments. You can then check what kind of encoding is used (typically it'll be base64) and what's the line length — that typically is fixed for an attachment, or even for all attachements. From this, you can deduce the exact ratio binay size/transmission size. If you don't care about that high precision, for base64, the estimated ratio 3/4 will be very close.

And from this, you can calculate a very good estimate of the size of a decoded attachment.

In reply to Re^2: How to find the size of an attachment in a POP3 server by bart
in thread How to find the size of an attachment in a POP3 server by Satish@Stag

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.