Learn English – What to capitalize if the title is a question

This Writer's Block page on capitalization sums up the rules in one page which is the most useful that I have found, basically these rules from the Chicago Manual of Style plus a number of minor rules which are worth reading:

1. Always capitalize the first and the last word.
2. Capitalize all nouns, pronouns, adjectives, verbs, adverbs, and subordinate conjunctions ("as", "because", "although").
3. Lowercase all articles, coordinate conjunctions ("and", "or", "nor"), and prepositions regardless of length, when they are other than the first or last word. (Note: NIVA prefers to capitalize prepositions of five characters or more ("after", "among", "between").)
4. Lowercase the "to" in an infinitive.

There may be some exceptions, but in titles I would generally capitalise as E-Learning.

The first page of Google Books results:

• 6 x e-Learning
• 4 x E-Learning
• 0 x E-learning

This one page is a too small sample, but you can check a number of books and see how it has been used in various places.

If there's a clear accepted form for any given e- word, then use that. Otherwise, I think the key is to to pick a style and use it consistently.