I heard someone say this in an interview the other day.

Problem:
The adverb “back” in “reciprocate back” is redundant.

Explanation:
I heard an Internet-marketing guru make the statement “They’ll reciprocate back for you.” in an audio file recorded as part of an interview series sponsored by Brad Callen, the maker of Keyword Elite.

The verb “reciprocate” when used without an object usually means to make a return, so the meaning of “reciprocate back” would be to make a return back.

Because the “re” in “return” means back, one could argue that someone who “reciprocates back” would never make a return (e.g., for something given).

For fun, I searched Google for the expression “reciprocate back” (with the quotation marks, to avoid variations) and got about 7,920 matches, which is relatively low.

I continue to believe that the growing tendency, at least in American English, to add the adverb “back” after many “re” verbs reflects a growing ignorance about the meanings of the roots of English words.

Solution:
“They’ll reciprocate for you.”