Yahoo! Mail Watcher

   Secure check new Yahoo! Mail

    Yahoo! Mail Watcher is an add-on for Firefox, Palemoon and Seamonkey.

    If you want Yahoo! Mail Watcher Extension for Chrome or SRWare Iron, please click here

    (Please note that this product is not from Yahoo or Google. It was made by Sonthakit Leelahanon).

Mirror for download
    Latest version 2.29
    Size 269,284 bytes.
    Release date 30 Jan 2016
    Work with Firefox 4 - 45 (and possible later version)
    Work with SeaMonkey 2.1 - 2.39 (and possible later version)
    Work with Palemoon 25 - 26 (and possible later version)
    MD5 - ae59cb7da7dfe41fa20cf3cfc5c06a75
     Screenshot             Change Log             Older version            Statistic

Important Note for Firefox User

Direct install from this site is not allowed in current version of Firefox. You need to do a manual install from file by download the file (xpi type file) to your computer. Usually download the file from mirror site is work. Then open Firefox. Open the Add-on Manager by press Shift-Control-A (or type about:addons at URL bar). Click the "Tool for all add-ons" icon (Gear icon).,Click the "Install Add-on from file...". And choose the downloaded xpi file.


Watch for your Yahoo! Mail and report to you in status-bar and toolbar.

Check Yahoo! Mail at specific interval ( 1 min, 2 min, 3 min, 4 min, 5 min, 10 min, 15 min, 20 min, 30 min, 1 hour or manually).

Automatic recheck (update counter) when last tab of Yahoo! Mail is closed.

Can select to alert by sound, by notification window or by blinking icon.

Can select to alert only inbox or all folders (except Junk, Drafts, Sent and Deleted).

Can select to alert unread email or newly arrived email (by increasing unread email count method).

Sound can be selected to be "build-it" or "system" (control panel setting) or "custom sound".

Use secure protocol - HTTPS-SSL to connect to Yahoo! Mail server. Safe from eavesdroppers.

No unnecessary action take. Simple is the rule.

High security. No need to input username and password. Nothing storage.

This extension use Browser cookie to get information. So, security level is the same as Yahoo! Mail website security.

This extension work only after you log on at the Yahoo! Mail website. As long as you stay log on, this extension still work.

If you log out from Yahoo! Mail website, this extension log out too !

Private browsing mode compatibility. "Yahoo! Mail Watcher" will not leave any traces after you stop private browsing.

Trustworthy because "Yahoo! Mail Watcher" is the open source extension.

How to Use

Left click at the icon on the status (Add-on) bar or toolbar to open Yahoo! Mail website.

Right click at the icon on the status (Add-on) bar or toolbar to open popup menu to change options.

Middle click at the icon on the status (Add-on) bar or toolbar to check email now.

If this add-on does not work or you have other troubles, please right click at the icon and select help.


Some report problem about incomplete loading of email when left click. This problem occur with option "Reuse existing mail tab first". The reason for this error is still unknown. Disable this option can solve the problem. (Thank to Chris Moore).

Due to this add-on was first created for Firefox only (Seamonkey support was add later), all of this page and help are Firefox reference. For Seamonkey, please apply.

The purpose that I make this Add-on is security. Please do not ask me to include "Log in feature". Because I don't want to be the cause of leakage of your storage username and password!

Checking email often than 3 minutes can cause "DoS attack (Denial-of-service attack)" to Hotmail server. So, please use these very frequently checking option only when you really need.


Q - Cannot install, only download happen. How can I do a manual install?
A - Sometime, click to install may not work. Instead of install, your browser just download it. If this happen, you need to do a manual install which can do in 3 ways.
  1. Open the Add-on Manager by press Shift-Control-A. Click the "Tool for all add-ons" icon (Gear icon).,Click the "Install Add-on from file...". And choose the downloaded file.
  2. Open a file explorer, find the downloaded program, and drag it into a Firefox window. What is on the Firefox window does not matter.
  3. At menu of Firefox, click "File" and then click "Open File..." [ or simply press control-O ] and then select the downloaded file.
Q - Is this add-on auto-update?
A - If you use version 2.10 or later, it will auto-update.

Q - Is this add-on signed by Mozilla?
A - Version 2.28 and later are signed.

Q - Why this add-on is not host on Mozilla?
A - This is a long story. In the past, it was hosted on Mozilla like other add-ons. The conflict began with a rapid release cycle of Firefox and one of my add-on "bookmark favicon changer". This made me headache to fix the bug every 6 weeks when the new version came. Look, I am an ordinary man which can sick and die. I also have a regular busy job. Developing the add-on is only a hobby in free time. I cannot follow this rule. I need Firefox to have a "backward compatibility" like Chrome. I complain this to Mozilla but no response. And finally, when Firefox 22 was released, the bug fixing was impossible without the using of dangerous javascript code "ProcessNextEvent". So I quit and change my default browser to SRWare Iron. I also developed all of my Add-on for Chrome version for my use and public released it. After I quit, for about 6 months, no one can fix "bookmark favicon changer for Firefox" and there was no any other add-on can do this job. I had received a lot of emails complain about this. I always said that I couldn't fix it. But one user told me that he didn't need a perfect add-on, just stable enough. He wanted to try and took a risk. So I released the new version 2.00 which used the dangerous code "ProcessNextEvent" and I hosted it on on my site. It turned out to be a quite stable add-on. For protesting Mozilla for not having "backward compatibility mind", I continued to host the new versions on my site. Finally, on 22 July 2014, Mozilla disable (banned) all of my add-on at their site. The reason that they tell me was "I do not upload new version to them" And "I use Mozilla as a link to go to my site". You may think that I am wrong. Yes, may be. But no matter what it is, at this time, I feel "Freedom", and it is good. Another thing is... I think it is not fair for Mozilla if I don't include the comment from them. You can read the discussion and reply from Mozilla AMO Chief Editor "Jorge Villalobos" at here. You will see that my add-ons were not banned because they were harmful. If you still suspect that my add-ons are not safe, please read the source code by yourself.

Q - Is it better to have someone review this add-on before publishing like Mozilla do?
A - Seem like that. But if you know the truth about Mozilla reviewing process, you will be surprised. First, Reviewers are volunteers, which can be anyone including developer himself. Second, from my experience, reviewing process could take time from 10 seconds to 4 weeks. How could you trust reviewer who review add-on by using only 10 seconds? And how could you tolerate the bug fix version which released very late on  the next month? If you don't believe me, you can see the example of "Add-ons Update Report" from Mozilla at here.

Q - You say it is open source. How can I read the source code?
A - Add-on itself is a source code. If you want to read it, you need to download the add-on first (usually by go to mirror site). You will get one "XPI" file which you can do a manual install (see above FAQ). But instead of install, you rename it to "ZIP" file. Then unzip it, you will get all of source codes.

Q - There is a link to website "" in your source code. It look suspicious. Why?
A - It is for auto-update process. I need to download "RDF" file to check for latest version which is host on this site. I use "" as an intermediate redirection site to get anonymous statistic. is a very free popular third party website, anyone can use it. Connection to is also on a secure channel "SSL-HTTPS". This statistic is opened and public, you can see the statistic and target redirection URL at here. Please note that It is not just me that record anonymous statistic, Mozilla themselves also record anonymous statistic when add-on check for update. 

Q - What license this add-on use? Can I modify or improve it?
A - This add-on is full copyright because I don't want to donate it to Mozilla. But don't worry, I allow you to do anything to my add-on, including edit, modified, publish, copy, distribute as long as it is free and you include my name for credit of creation of this add-on. The most important point of this copyright is "Don't donate it or part of it to Mozilla".

Q - Why is it free? Is it free forever? Are you making money from this extension?
A - It is free because I want to "make the world a better place". It will be free forever except if there is a gun pointed to my head (not literally, of course). And I do not make any money from this extension. I do not involve other websites that use my extension to promote their websites for other purposes, and I do not get paid.

Q - Can I donate to you? Can I help you in any other way?
A - No, I don't want any donation. If you want to help, just help other non-profit organizations with your computer. I suggest Boinc which uses the idle time on your computer for scientific research.

Q - I have another question. Can I contact you?
A - Yes, please contact me by email at