Please give us more details. I tried running the regex against "z" or " " in 5.18.2 and blead, but the results are consistent across Perl versions.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

The test was at https://www.hackerrank.com/challenges/detect-the-email-addresses/problem

This might be in a state of flux. I am getting a 404 error trying to load the example docs I had from before. As I mentioned, I have an open ticket on this issue, as my opinion is that if they offer 'tests' then their tests should perform exactly like the languages they are testing.

The code I wrote was such:

#!/usr/bin/perl

use strict;
use warnings;

my (@res);
while(<>){
    my @add = $_ =~ /([\w\.]+\@[\w]+\.[\w]+.*?)[^\w\.]/g;    
    $_ =~ s/\.$// for @add;
    push @res, @add;
}
my %uniq;
$uniq{$_}++ for @res;
@res = sort  keys %uniq;

print join ";", @res;
[download]

The input data was this:

51
E-MAIL ADDRESSES OF GMs AND DRMs ON IR
RLY    GM E-Mail    Division    DRM E-Mail
CR    gm@cr.railnet.gov.in    Mumbai    drm@bb.railnet.gov.in
Bhusawal    drm@bsl.railnet.gov.in
Pune    drm@pa.railnet.gov.in
Nagpur    drm@ngp.railnet.gov.in
Solapur    drm@sur.railnet.gov.in
ER     gm@er.railnet.gov.in    Howrah    drmhwh@er.railnet.gov.in
Sealdah    drmsdah@er.railnet.gov.in
Asansol    drmasn@er.railnet.gov.in
Malda    drmmldt@er.railnet.gov.in
ECR     gm@ecr.railnet.gov.in    Danapur    drmdnr@ecr.railnet.gov.in
Dhanbad    drmdhn@ecr.railnet.gov.in
Mughalsarai    drmmgs@ecr.railnet.gov.in
Samastipur    drmspj@ecr.railnet.gov.in
Sonpur    drmsee@ecr.railnet.gov.in
ECoR        gm@eastcoastrailway.gov.in      Khurda Road    drmkur@east
+coastrailway.gov.in
Sambalpur    drmsbp@eastcoastrailway.gov.in
Waltair    drmwat@eastcoastrailway.gov.in
NR     gm@nr.railnet.gov.in    Delhi    drm@dli.railnet.gov.in
Ambala    drm@umb.railnet.gov.in
Moradabad    drm@mb.railnet.gov.in
Lucknow    drm@lko.railnet.gov.in
Ferozepur    drm@fzr.railnet.gov.in
NCR        gm@ncr.railnet.gov.in      Allahabad    drm@ald.railnet.gov
+.in
Jhansi    drm@jhs.railnet.gov.in
Agra    drm@agc.railnet.gov.in
NER    gm@ner.railnet.gov.in    Izzatnagar    drmizn@ner.railnet.gov.i
+n
Lucknow    drmljn@ner.railnet.gov.in
Varanasi    drmbsb@ner.railnet.gov.in
NFR    gm@nfr.railnet.gov.in    Katihar    drmkir@nfr.railnet.gov.in
Alipurduar    drmapdj@nfr.railnet.gov.in
Tinsukhia    drmtsk@nfr.railnet.gov.in
Lumding    drmlmg@nfr.railnet.gov.in
Rangia    drmrny@nfr.railnet.gov.in
NWR    gm@nwr.railnet.gov.in    Jaipur    drmjp@nwr.railnet.gov.in
Ajmer    drmaii@nwr.railnet.gov.in
Bikaner    drmbkn@nwr.railnet.gov.in
Jodhpur    drmju@nwr.railnet.gov.in
SR    gm@sr.railnet.gov.in    Chennai    drmmas@sr.railnet.gov.in
Madurai    drmmdu@sr.railnet.gov.in
Salem    drmsa@sr.railnet.gov.in
Palghat    drmpgt@sr.railnet.gov.in
Tiruchirapalli    drmtpj@sr.railnet.gov.in
Trivandrum    drmtvc@sr.railnet.gov.in
SCR    gm@scr.railnet.gov.in    Secundrabad    drmsc@scr.railnet.gov.i
+n
Hyderabad    drmshyb@scr.railnet.gov.in
Guntkal    drmgtl@scr.railnet.gov.in
Guntur    drmgnt@scr.railnet.gov.in
Nanded    drmned@scr.railnet.gov.in
Vijayawada    drmbza@scr.railnet.gov.in
[download]

The expected results were:

drm@agc.railnet.gov.in;drm@ald.railnet.gov.in;drm@bb.railnet.gov.in;dr
+m@bsl.railnet.gov.in;drm@dli.railnet.gov.in;drm@fzr.railnet.gov.in;dr
+m@jhs.railnet.gov.in;drm@lko.railnet.gov.in;drm@mb.railnet.gov.in;drm
+@ngp.railnet.gov.in;drm@pa.railnet.gov.in;drm@sur.railnet.gov.in;drm@
+umb.railnet.gov.in;drmaii@nwr.railnet.gov.in;drmapdj@nfr.railnet.gov.
+in;drmasn@er.railnet.gov.in;drmbkn@nwr.railnet.gov.in;drmbsb@ner.rail
+net.gov.in;drmbza@scr.railnet.gov.in;drmdhn@ecr.railnet.gov.in;drmdnr
+@ecr.railnet.gov.in;drmgnt@scr.railnet.gov.in;drmgtl@scr.railnet.gov.
+in;drmhwh@er.railnet.gov.in;drmizn@ner.railnet.gov.in;drmjp@nwr.railn
+et.gov.in;drmju@nwr.railnet.gov.in;drmkir@nfr.railnet.gov.in;drmkur@e
+astcoastrailway.gov.in;drmljn@ner.railnet.gov.in;drmlmg@nfr.railnet.g
+ov.in;drmmas@sr.railnet.gov.in;drmmdu@sr.railnet.gov.in;drmmgs@ecr.ra
+ilnet.gov.in;drmmldt@er.railnet.gov.in;drmned@scr.railnet.gov.in;drmp
+gt@sr.railnet.gov.in;drmrny@nfr.railnet.gov.in;drmsa@sr.railnet.gov.i
+n;drmsbp@eastcoastrailway.gov.in;drmsc@scr.railnet.gov.in;drmsdah@er.
+railnet.gov.in;drmsee@ecr.railnet.gov.in;drmshyb@scr.railnet.gov.in;d
+rmspj@ecr.railnet.gov.in;drmtpj@sr.railnet.gov.in;drmtsk@nfr.railnet.
+gov.in;drmtvc@sr.railnet.gov.in;drmwat@eastcoastrailway.gov.in;gm@cr.
+railnet.gov.in;gm@eastcoastrailway.gov.in;gm@ecr.railnet.gov.in;gm@er
+.railnet.gov.in;gm@ncr.railnet.gov.in;gm@ner.railnet.gov.in;gm@nfr.ra
+ilnet.gov.in;gm@nr.railnet.gov.in;gm@nwr.railnet.gov.in;gm@scr.railne
+t.gov.in;gm@sr.railnet.gov.in
[download]

My results in a shell are identical to those results. The missing address is the 'drmbza@scr.railnet.gov.in' in their minds.

It seems the behaviour depends on whether the file ends in a newline or not, not on the Perl version. That's because the final [^\w\.] has nothing to match if there's no newline.

If you are curious, here's my solution from three years ago:

<Reveal this spoiler or all in this thread>

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]