I don't know how you wish to use the data but to split out each character group 
(Except "UFOFH")into an array try this snippet

$_='UFOFH 33603 01231 /0000 0024/ 1024/ 2025/ 3027/ 4030/ 5025/ 6028/ 7060/ 8081/ 9098/ 0110/ 1107/ 2106/ 3102/ 4080/ 5065/ 6057/ <\p>';

my @mailbox=( m#([0-9//]{5})#g);

for my $i (0 .. $#mailbox) {
  print "mailbox[$i] =>  $mailbox[$i]\n";
};

which results in

mailbox[0] =>  33603
mailbox[1] =>  01231
mailbox[2] =>  /0000
mailbox[3] =>  0024/
mailbox[4] =>  1024/
mailbox[5] =>  2025/
mailbox[6] =>  3027/
mailbox[7] =>  4030/
mailbox[8] =>  5025/
mailbox[9] =>  6028/
mailbox[10] =>  7060/
mailbox[11] =>  8081/
mailbox[12] =>  9098/
mailbox[13] =>  0110/
mailbox[14] =>  1107/
mailbox[15] =>  2106/
mailbox[16] =>  3102/
mailbox[17] =>  4080/
mailbox[18] =>  5065/
mailbox[19] =>  6057/