Originally Posted by Bowgie

By "Delta code", you mean your Skymiles number on your receipt or boarding pass? That does not matter either way in my experience. If it is missing, you can still claim the miles. If your Skymiles number is on your boarding pass, it is still more likely than not you will not get Skymiles credited.

If you mean by "code" the flight number something like AMxxx? There cannot also be a DLxxx number attached to the flight. It is an either or thing. If many cases, but not all, you get more miles if the flight is coded (technically "marketed as") AMxxx. None of this affects whether or not Skymiles post, just the amount of the miles.

For myself, I always book flights as AMxxx right on AeroMexico's website, and my correct Skymiles number is always on my boarding pass. It does not make a difference because AeroMexico never posts to my Skymiles account. This is several flight per year, and yes, I am fed up with Delta.

I have to go through this process with Delta:
1. After a few weeks, post my missing miles claim on Delta.com with a pdf scan of my boarding passes.
2. Wait another month. I may or may not get an e-mail acknowledgement from Delta, but most definitely there will be no further response from Delta.
3. Call Delta reservations. Explain that I did not get credited for a partner flight, and I sent in my boarding passes a month ago (now two months ago since my flights)
5. Repeat daily until I get an agent who cares or is knowledgeable enough to get me the secret email address of the ONE person at Delta Air Lines who can manually fix this.
6. Send in boarding passes to secret address, and see my miles magically appear the next day.

Do not let the time allowed for steps 1 though 6 exceed nine months (used to be one year), because that is the hard and fast time limit for claiming missing Skymiles.
Good luck and be persistent.

In the old days, Delta had a published fax number where you could send in your partner boarding passes and be credited within a week.
This is a Delta problem. They own 25% of AeroMexico (used to be 49%, but AM went bankrupt in the pandemic).
Delta also has an ownership interest in LAN, but their flights credit same or next day.

Call me cynical, but this is a problem Delta has little interest in fixing. Oh, and the short answer to OP's question, "How long does it take for AeroMexico flights to post to Skymiles?" Answer: "Never, unless you chase them down from Delta like a crazed badger."