Spell Check is Available for iCloud mail:
Spell-check an email
If you’re using iCloud Mail in Safari or Firefox on a Mac, you can check an iCloud email message for spelling errors using the browser's spell-checking feature.
If you’re using a different web browser, check the browser’s preferences or menus to see if it has its own spell checker.
Hide Check spelling
- If you’re using Safari, choose Edit > Spelling and Grammar > Check Spelling While Typing. If you’re using Firefox, choose Firefox > Preferences. In the General pane, select the “Check my spelling as I type” checkbox.
- Compose a new message or open a message whose spelling you want to check.
Questionable spellings in the message are underlined with a red dotted line.
Control-click a misspelled word, then choose one of the following options from the menu:
To accept a suggested spelling, choose the word you want.
To leave the current spelling as it is, choose Ignore Spelling.
- Repeat step 3 for each underlined word to correct all of the spelling errors in the email message.
Safari offers additional spell-checking options, which you can also choose from the Edit menu.
I've had a lot of problems with the cursur staying in the correct position as I type in iCloud's Mail program. I use a Windows 7 PC and instead of writing my e-mails in iCloud, I write all my e-mails (new, replies, forwards, etc.) in MS Word and use its spell check. I find it to be easier to type accurately in Word (the cursor is stable) and it's spell check is superior to those offered by browser spell checks. After I've finished writing my e-mail in Word, I simply copy and paste it into the iCloud e-mail. There's another added benefit to doing this. That is, the writing can be formatted much better and easier in Word so when you paste your document into your e-mail all the Word formatting pastes into the e-mail too, giving the e-mail a much more professional look than using the bare bones formatting capabilities within the iCloud Mail program itself.
Hope this helps.