Php grabs a word of the string, does not replace it, and adds <br>

assume that the string is 

abc@gmail.com
    Can
  1. realize the name of the string before catching @? (abc) no matter how long.
    2. Can
  2. automatically add a
    before each string @? It will not replace any Kansi. 
abc
@gmail.com
Php php7 string
Mar.01,2021
$abc = "12ww@qq.com";
$a = strpos ($abc, "@");
$str = substr ($abc,0,$a). "
" .substr ($abc,$a); 

$email = 'abc@gmail.com';
$email = str_replace("@","<br>@",$email);

$email = 'abc@gmail.com';
$arr = explode ("@", $email);
echo $arr [0], "
",' @'. $arr

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1be8141-31120.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1be8141-31120.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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