Sometimes simply resending them doesn't fix it.Go to options>advanced options>service books and find the yahoo service books and delete them.Your mail icon will completely disappear,then go to setup>manage internet email>and resend service books.
Both me and my wife have the Bold 9700 running on OS 5.0.0.442. Strange part is, I'm having the disappearing yahoo mail icon. My wife's device has the icon appearing from day 1 even after loads of soft reset or battery pull.
I also have a few friends having Onyx running the same OS without this issue. This got me thinking that this is not OS related.
Re-sending service books can be annoying at times and will just have to stick with the default mail icon for now.
I have 3 accts, BB, hotmail and gmail. When I set a theme I have the themes custom icons, then ONLY the gmail will change into the stock Envelope/globe icon. I fixed this by deleting the enhanced gmail plugin and it hasnt happened since.
i rebooted my 9700, and the yahoo mail icon disappeared again, did another round of deleting my yahoo mail service books, then re-sending it, it worked again!
just go to the yahoo icon on your menu and press the menu key when you are on it, it is hidden thats why it shoes the dull color. click show all and click hide till you dont see check marks on itin front of the two options , i got this after 2 months of seeking for answers