Spell Checker page (Preferences dialog box)
In this page, you can set spell checker options.

Ignore words with numbers
Check this option to skip any words containing embedded digits.
Ignore URLs and E-mail addresses
Check this option to skip URLs and E-mail addresses.
Ignore all-caps words
Check this option to skip words that contain only capital letters.
Ignore mixed case
Press this button if you want to skip words that contain uppercase letter other than the first letter. For example ScanDisk, WordPad, etc.
Skip HTML tags
Press this button if you want to skip words inside HTML tags.
Check the Latin alphabet only
Press this button if you want to check the Latin alphabet (ISO 8859-1) only and skip other languages.
Dictionary
Choose dictionary to use with the spell checker. Currently EditPlus provides US English and UK English dictionaries only.
User dictionary
User dictionary file is a plain text file that has ".USD" extension. You can add items into this file by Add or Add Uncap command in the Spell Checker dialog box.