Delta just told me (in the customer service letter above) that I can.

This all came up because I asked about bikes to a bunch of different DL agents on the phone, and came up with a bunch of different answers. I have a bike box now (that looks like a large suitcase) that's 88 linear inches, and I'm looking forward to seeing whether they charge me as a bike, charge me as an oversized, or don't charge me for anything (per their email/website). I'm going to print out the email and the website, and try to avoid the fee

DL really does a bad job organizing/presenting their policies......