Yahoo recommends you upgrade your browser to enjoy all the features in the new Yahoo Mail.

[throkr]

In addition to my previous posts: I tested this with Chromium and this issue doesn't appear.
So, the problem seems clearly to be on Iron's side .....

[CorbN]

Here is a working solution (I use it myself):

1. Install user agent switcher for Chrome

2. Choose a user agent from this page (I'm using Chrome 70 for Windows 10 = Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36) and add it to the general list (this way the user agent is only changed for this one page and is remembered; the general user agent is not modified).

3. Add "mail.yahoo.com" (or "login.yahoo.com") combined with the new string you just added to the permanent spoof list.


That's it: now you should be able to login to the new yahoo mail without any problem!

Hope this helps ...

Thanks buddy !
Works also for me You made my day !

[throkr]

I found another (better) solution to this problem without the need of a special add-on; this is also permanent and works fine.

- launch the "Iron Config and Backup tool" (located in the Start Menu), tab "user agent", replace the user agent string with a new one (I use: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3750.0 Safari/537.36 for the actual latest version), create a new shortcut with this new string.

- now you can permanently launch Iron from this shortcut (delete the old one, if you like).

Hope this helps.

[dinkydau]

In addition to my previous posts: I tested this with Chromium and this issue doesn't appear.
So, the problem seems clearly to be on Iron's side .....

It's not a problem with iron. It's a problem with yahoo. They're being dicks by refusing service to users of Iron. Any website could do that with any browser. It means that all iron users that have yahoo mail need to be dishonest about the browser they're using.

I prefer the solution using the extension because changing the user agent of the entire browser affects other websites unnecessarily and makes iron count as chrome in statistics.

For yahoo I use this user agent string just in case they ever do some research and a person happens to see it:
Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.124 Safari/537.36 (This is SRWare Iron but you won't let me access web mail otherwise.)