Output redirection to a file, used inside script, is not working when executed from crontab

The script is working when executed from terminal but, it's giving "(CRON) info (No MTA installed, discarding output)" information when executed from crontab.

Below are my script contents. I have 2 scripts, and a master scripts which executes these two scripts sequentially. You can create them as it is in your system too for testing. I haven't written anything complex here.

testpad1.sh. Script is written with error intentionally.

#!/bin/bash
echo "This is script one.
sleep 3

testpad2.sh

#!/bin/bash
echo "This is script two"
sleep 3

masterpad.sh

#!/bin/bash
mkdir -p logs
./testpad1.sh &> logs/testpad1.log
echo `date`
./testpad2.sh &> logs/testpad2.log
echo `date`

As you can see, the script masterpad.sh redirects other two scripts' output to their respective log files.

Here is the cronjob.

* * * * * /opt/scripts/masterpad.sh

It's working without issues when executed from terminal, by creating testpad1.log and testpad2.log along with expected output.

But if I schedule the same in crontab, it's giving "(CRON) info (No MTA installed, discarding output)" error. This error was checked by excecuting, "grep CRON /var/log/syslog".

Thank you.

Update

Since a user in comment section doubted this post with other post, Below is the output to show that, error was not there previously but have occurred only after I added the cronjob. This is the previous output of "grep CRON /var/log/syslog" command.

CMD (/opt/scripts/masterpad.sh &> /opt/scripts/logs/masterpad.log)
CMD (/opt/scripts/masterpad.sh)
CRON[6656]: (CRON) info (No MTA installed, discarding output)
CRON[6733]: (padmahasa) CMD (/opt/scripts/masterpad.sh)
CRON[6732]: (CRON) info (No MTA installed, discarding output)

Update 2: Summarized answer from comments and accepted answer.

To get both STDOUT and STDERR from other scripts that are invoked from master script or command (which crontab executes), can use both "&>" or still better option "|& tee" redirection or you can use any other suitable option as in this table but, to capture STDOUT and STDERR of master script or command, "/absolute/path/to/script > absolute/path/to/logfile 2>&1" is the only format that works. Hence the modifications to

1. masterpad.sh

#!/bin/bash
mkdir -p logs
./testpad1.sh |& tee logs/testpad1.log
echo `date`
./testpad2.sh |& tee logs/testpad2.log
echo `date`

2. crontab job

* * * * * /opt/scripts/masterpad.sh > /opt/scripts/logs/masterpad.log 2>&1

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