I immediately replied with a permutation of her name (first initial plus last name) which had exactly eleven letters. Then I said:
Coincidence? I don't think so. I'd better call the FBI "really quick" (another 11 letters) to help them "investigate" (oh no, another 11 letters - they must be in on the plot too! AAAAAAAAACK!!!!!!!!!!!).I signed off with a common presentation of my own name that also came to exactly 11 letters, followed by a quick postscript: "And in an odd coincidence, 'coincidence' has 11 letters too."