My prefix bends bridges and branches in dozens.
My suffix sends mail with what one-hundred governs.
My infix appears three times, hectic and scattered.
I meet engineers, for the looks always mattered.
This might be pretty easy... but that won't receive the $100$ rep bounty award.
You would have to find a secret word in this riddle, involving the numbers, if you want that award.
The numbers also include $16$.
I would give out $50$ instead, but it was my birthday recently, so I am being kind :) Note: This is genuinely true and not part of the riddle.
$100=10\times 10$... but that is not necessarily true for Romans.