What's represented by the fifth letter in email? (10)

I believe the answer is:

electronic

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But I can't explain it at all! Could you help me understand?

(Other definitions for electronic that I've seen before include "of some modern technology" , "Like a computer" , "Relating to micro-circuitry" , "of PC devices?" , "Like microcircuitry" .)

I've seen this clue in The Telegraph.

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