I tried: ...

Exactly what code did you try? On exactly what data? Please see Short, Self-Contained, Correct Example.

( $sender ) = split (/\s(sender=(.*)@(.*),)/);

This doesn't look like a sensible split invocation. Have you read and understood the split documentation?

client_address=185.15.51.41, EMPTYFROMHERE

I don't understand where this extracted substring comes from; the substring  EMPTYFROMHERE appears nowhere in the OPed data. Again, Short, Self-Contained, Correct Example. Please help us to help you.

Online Regex tools tell me that all is great.

Which online regex tools? How does their advice apply to the operation of split?

Give a man a fish:  <%-{-{-{-<

In reply to Re^3: Array of strings search by AnomalousMonk
in thread Array of strings search by maikelnight

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.