Thanks, great tip - both of you, for telling me what the character numbers were that were replacing those carriage returns in the Access memo field, and for suggesting the replace() function.
I used the following nested replace in my query, it even worked around the results of my iif() function - to replace the multi-line characters with a "," and " " for a much smoother export.
eg: A query to pull the correct address from a record now contains this:
Mailing address: Replace(Replace(IIf[Address] Is Null,[address2],[address]),Chr(13),","),Chr(10)," ")
There are probably a number of permutations that would have worked in this situation. (like putting the "replace" within the iif - but I'd have had to do it for both fields then)! So thanks for the tip.