The rule is that "ei" is pronounced as [i:] only after letter c (or what is pronounced as [i:] is written as "ei" after letter "c" only).
There are exceptions, that I could find so far, like
- foreign (possibly),
- either (possibly),
- neither (possibly),
Can you add more exceptions to this list?
I am not that much interested in differences of pronunciation between different dialects of English but about helpful (for me) mnemonics for written English.
Once more, this question is not on orthography but on mnemonics to help in writing.
If you know any other helpful mnemonics to deal with spelling of words with "-ie-" and "-ei-", you are welcome to answer this question.