Yes, as long as you have online access to the account.

Is still the latest to not ask Delta or have there been any recent reports of successfully transferring to a spouse at the same mailing address?

Any datapoints on if we can close the DL AMEX account via the death process or should I try to close via secure message or calling in without noting the death? Previous datapoints said AMEX notified Delta of the death.

Use up all the miles before notifying DL or Amex. I would pay off the Amex bill and not use the card before notifying them to avoid losing all the miles.

Sorry for your loss. So many things to deal with on top of the grief.

Can you transfer points to your own airline account via online transfer if logged into the Amex account? For example, I can transfer points to my spouse’s delta account. If not, then I think I’d transfer to account owners airline account and simply close the card via chat without providing a reason other than simply don’t want it anymore.

For AMEX, be slightly cautious about how many accounts or how many transactions you do. I had to move 1.5M AMEX MP points last year, and once I had added three siblings Delta, BA and HI accounts and started moving miles two moves in we got locked out of additional moves and had to go through a fraud protection process with AMEX on the phone. Fortunately, there was another authorized USER on the account who was able to release the fraud control and we could continue to move miles.

Are you talking about Delta Sky Miles or Amex points? Two different things. Delta (according to the T & C's) consider the miles to be Delta's until they are used. If someone passes away, Delta feels the miles are theirs and they won't transfer them to anyone else. If you have access to the delta.com account, you should be able to use the miles without any issues. Just don't tell Delta the person is deceased. If you are talking about Amex points, that is different. One way or the other, if you cancel the Amex card, Amex will not contact Delta to advise them of the death. My wife passed away 2 1/2 years ago. I cancelled her Amex and continued to use her Delta miles until they were depleted.

All airlines consider miles theirs. If they did otherwise they would invite taxing to be involved. (Plus other legal/accounting issues)

As for AMEX. There's been rumors, but AFAIK nothing proven. I highly doubt they would notify DL. Banks have significant restrictions on what information they can share, especially with outside non-financial businesses.