Depending on what it's for you can add it as a link in:

/templates/template_name/includes/menu.tpl for the main menu or the following for the top right toolbar:

/templates/template_name/includes/toolbar.tpl

<li><a href="{$WEB_ROOT}/index.php?m=clientnotify">Notification Settings</a></li>

When the website goes down, does the system automatically recheck to confirm before sending an alert to the customer?

ANS: Yes, if the website is down then it will check other locations to be sure that it is offline. If it is offline on all locations then it will report the monitor as DOWN otherwise if even 1 location finds it up then it will report it as ONLINE.

You can define one-time and recurring maintenance windows to pause uptime checks. We will not send you downtime alerts on planned outages.

Blacklist (DNSBL) Monitoring service will ensure the IP of your mail server has not fallen into one of the major DNSBL (DNS-based Blackhole List) blacklists.

Email blacklist check is vital for your business because if your server is blacklisted, spam filters might block some or all of the emails that your servers send out.

One the monitoring servers, do you need any software to be installed? What OS and server specs must those monitoring servers contain? What if the server is being overloaded, how will i know that? 

ANS: The system is built for Apache and is tested on cPanel with Apache. I do not believe that it matters which version of Linux OS you have installed. I am unable to recommend a specific hardware specification as we have not had any reports of any of the monitoring services over-loading any servers. An average medium VPS should be enough for your WHMCS + The monitoring module. You do not need to install any further software presuming you have PHP and MySQL Installed as required by WHMCS.

If this was monitoring 1000 sensors, how much traffic will it generate? How much CPU will it use? How much memory will it use?

ANS:  In server monitoring we have some solution to check from multi locations and some times it's taking while to finish in all location then we recommend don't use lesser then 5 minutes monitors to all can working right, about the CPU it's don't cost many process

If this is hosted on a cPanel server with 50 other sites (where WHMCS is hosted) how much impact will it have on the other sites if CloudLinux is not used?

ANS: there is no problem to you use in shared hosts but we recommend to use in VM or dedicated, everything about the processing time and how much servers need to monitor, I can tell if you have many monitors you time is important and other is OK

Version: 2.1.4 Released (12/01/2021)
Maintenance

Fixed Problem with WHMCS v8 gateways
Updated About Page
Updated Remove Support for PHP 5.6 to 7.0

Version: 2.1.3 Released (04/02/2018)
Maintenance

Update to work with WHMCS 7.5
Update to work with PHP 7.2 and Ioncube 10.1

Version: 2.1.2 Released (14/10/2017)
Maintenance

Updated Improve License Check
Updated WHMCS v7.3 support
Updated Make working with PHP 7 and Capsule
Updated WHMCSSERIVCES help page added

Version: 2.1.1 Released (10/10/2016)
Maintenance

Updated WHMCS v7 support

Version: 2.1.0 Released (25/10/2015)
Maintenance

Updated License Code

Version: 6.2.1 Released (01/03/2024)
Maintenance

Fixed support for ionCube Loader v13
Updated Licence System with Cloudflare
Updated Improve ionCube Loader

Version: 6.2.0 Released (11/28/2023)
Minor

Added A note on the Services page
Added Top bar to the top of the page
Added Support PHP 8.2
Fixed PHP 8.1
Updated Remove Support for WHMCS V8.4.x to 8.5.x

Version: 6.1.1 Released (12/04/2022)
Maintenance

Added Italian Language
Fixed issue with display popup in special pages
Fixed support for ionCube Loader v12 and PHP 8.1
Updated Remove Support for PHP 7.1 to 7.3
Updated Remove Support for WHMCS V8.1.x to 8.3.x

Version: 6.1.0 Released (12/29/2021)
Minor

Added Add fund page banner
Updated New WHMCSServices menu to work with WHMCS 8. x
Fixed Problem with PHP 7. x
Fixed Problem with popup predefined styles
Fixed Button Not Functioning

Version: 6.0.0 Released (09/22/2020)
Stable

Added Admin User with many updates and improvements
Added New predefined popup list
Added New template notification
Added Archive notification feature
Added Start at notification
Added Preview popup
Added index.php to all directories
Fixed Admin issues
Fixed htaccess rewrite URL
Fixed breaking the third-party WHMCS theme called Control (impressivethemes)
Updated Module tables renewed
Updated Remove v4 Admin theme from distribution
Updated Remove Support for PHP 5.6 to 7.0

Version: 5.0.7 Released (12/03/2018)
Maintenance

Fixed blank HTML paragraph

Version: 5.0.6 Released (08/03/2018)
Maintenance

Fixed third-party WHMCS theme called  SwiftModders Themes
Fixed Expiry Date

Version: 5.0.5 Released (07/26/2018)
Maintenance

Fixed Correct language in about page
Fixed Product group notification
Updated New WHMCSServices menu to work with WHMCS 7.6
Updated Show alert when template missing

Version: 5.0.4 Released (06/04/2018)
Maintenance

Fixed PHP 7.1 and PHP 7.2
Fixed to work with WHMCS 7.5

Version: 5.0.3 Released (06/11/2017)
Maintenance

Fixed an improvement running in WHMCS 7.4
Fixed links added to the top notification

Version: 5.0.2 Released (15/10/2017)
Maintenance

Fixed Default WHMCS hook conflict problem
Updated WHMCS SERVICES help page added

Version: 5.0.1 Released (13/10/2017)
Maintenance

Fixed Upgrade from the 4.0 version problem
Fixed None multi-language problem

Version: 5.0.0 Released (10/10/2017)
Stable

Added Top notification
Added Popup notification
Added Allowing the client to show notifications with shortcodes
Added Set of custom colors and font added
Added Multi-languages
Added Custom CSS
Added Show notification to a product clients
Added Show notification to an Addon clients
Added Auto adding codes to the template file
Fixed Product Group

Version: 4.1.0 Released (30/01/2017)
Updated

Updated Improve the license call

Version: 4.0.0 Released (22/12/2016)
Stable

Fixed Middle notification does not show
Updated CKEditor Update
Updated New and faster licensing system implemented
Updated V7 Comparability
Updated Duplicate Button
Added Full recode of module helping the performance

Version: 3.1.0 Released (22/10/2015)
Maintenance

Updated License Code

Global settings: