PHP: include variable in $_POST - php

Question

I have a table with some information from my database. I have buttons next to each row in the table. If the button is clicked it should send an email to the user. I can give each button a unique value but can not have this value in the if isset.... How should i get the value of the button name to be variable and how could i get the value at the end of my url.
echo "<table>";
echo "<tr><td>Naam</td><td>EmailAdress</td><td>Datum</td><td>Type</td><td>Producent</td><td>SerieNummer</td><td> imei</td><td>Manager</td><td>bevestigd</td></tr>";
while($row = mysqli_fetch_row($result)){
$sqlid = "SELECT Bevestigd FROM tbl_bevestiging WHERE IDbewijs = " . $row[0];
$resultid = mysqli_query($conn, $sqlid);
$row2 = mysqli_fetch_row($resultid);
echo "<tr><td>" . $row[1] . "</td><td>" . $row[2] . "</td><td>" . $row[3] . "</td><td>" . $row[4] . "</td><td>" . $row[5] . "</td><td>" . $row [6] . "</td><td>" . $row[7] . "</td><td>" . $row[8] . "</td><td>" . $row2 [0] . "</td><td><form method=\"post\"><input name=\"" . $row[0] . "\" type=\"submit\" value=\"" . $row[0] . "\"</form></td></tr>";
}
echo "</table>";
if (isset($_POST[$row[0]])){
$admin_email = "adminmail#mail.com," . $row[2];
mail($admin_email, "Ontvangstbewijs geleverde hardware herverstuurd", "url?id=" . $row [0] , "From:" . "example#email.com");
mysqli_close($conn);
}
?>

Answer 1

Theres a few things I think are worth pointing out firstly.
Table header tags should be in a THEAD tag. See example here.
Try and avoid SQLs within a loop. If possible create a SQL that does everything for you to reduce the number of queries sent to MySQL.
Ok back to your question. Personally, what I would do is have a FORM tag in a TD tag. This way each button can have it's own unique id set in a hidden INPUT tag.
For example:
<tr>
<td>
<form action="[[YOUR-PHP-FILE]]" method="post">
<input type="hidden" name="id" value="[[ID]]" />
<input type="submit" value="Submit" />
</form>
</td>
</tr>
That way you don't need to focus on the submit button but rather the id.