Check URL and mail to webadmin Bash Script - bash

Question

Here is my code which will hit URL and check URL is working or not and will mail to respective webadmins
#!/bin/bash
curl -s --head http://myurl | head -n 1 | grep "HTTP/1.[01] [23].." > /dev/null
if [ $? -eq 0 ]
then
url1="myurl2 is working fine"
else
url1="myurl2 is not working"
fi
curl -s --head http://myurl2 | head -n 1 | grep "HTTP/1.[01] [23].." > /dev/null
if [ $? -eq 0 ]
then
url2="myurl is working fine"
else
url2="myurl is not working"
fi
exec 1<>/dev/tcp/127.0.0.1/25
a=$(cat <<"MAILEND"
HELO local.domain.name
MAIL FROM: <send#mydomain.com>
RCPT TO: <recieve#mail2.com>
DATA
From: send#mydomain.com
To: recieve#mail2.com
Subject: test
$url1 $url2.
.
QUIT
.
MAILEND
)
IFS='
'
declare -a b=($a)
for x in "${b[#]}"
do
echo $x
sleep 1
done
How ever in Mail I am getting $url1 $url2
This must be due to $url1 & $url2 is not getting substituted in line $a
Can Someone please help
let me mention one thing "mail" or "sendmail" mails get spamed in my domain so sending mails with above method only works fine
I am expecting "myurl is working" " myurl2 is not working"
as myurl2 httpd service I have already stopped
Thanks

Answer 1

Replace
cat <<"MAILEND"
with
cat <<MAILEND
Putting quotes around the identifier to a "here document" signals to the shell not to expand any variables. This is explained in the "Here Documents" section of man bash

Answer 2

This is intended as an aside, but since comments don't support code formatting, posting this refactoring here.
( cat <<____HERE
From: send#mydomain.com
To: recieve#mail2.com
Subject: test
____HERE
while read label url; do
if curl -s --head "$url" | head -n 1 | grep "HTTP/1.[01] [23].." > /dev/null
then
echo "$label is working fine"
else
echo "$label is broken"
fi
done <<____HERE |
myurl http://myurl2
myurl2 http://myurl
____HERE
) | sendmail -oi -t
I am assuming that the labels cross-matching each other's URLs is unintentional and/or incidental and/or beyond my limited comprehension.