Airbnb has been providing an easy way to contact Airbnb guests via email - specialized email addresses (ex brian-zpwc12fq5e59xihd@guest.airbnb.com) for each reservation. This has been the primary way for us to deliver generated PIN codes and Access Instructions to Airbnb guests.
Airbnb removed this guest email feature on August 15, 2020
Because of this, we are only able to deliver generated PIN codes via Airbnb's messaging system.
To ensure that your generated PIN codes are able to be sent to your Airbnb guests, please log into the RemoteLock portal and follow these instructions to re-authorize your Airbnb account.
1. Once logged into your RemoteLock account, Click "Integrations:

2. Click the "airbnb" tile:

3. Click on your Airbnb account. If more than one is listed here, you must repeat this process for each one:

4a. If you see a warning that RemoteLock needs additional access, like this:

Before proceeding, please make sure that you are not already logged into Airbnb. Many customers have multiple Airbnb accounts, and we must make sure that we are integrating with the correct one.
Click the "Grant Access" button. This will allow RemoteLock access to send messages to your Airbnb guest.
Jump to Step 5 below.
4b. If you see a warning that the integration has lost its connection with Airbnb:

Before proceeding, please make sure that you are not already logged into Airbnb. Many customers have multiple Airbnb accounts, and we must make sure that we are integrating with the correct one.
Click the "Reconnect with Airbnb" button.
5. You may see a screen similar to this:

Click the "Allow" button. You should then be redirected back to the RemoteLock portal:

If you see the green "Connected" status and no warnings, everything is good to go! Your guests will begin receiving their generated PIN code and Access Instructions via Airbnb Messaging soon.
You can also enable Airbnb Messaging immediately if you'd like by clicking the Settings tab to the left.
Questions and Answers:
Q: My settings show that guests will be emailed the PIN code a certain number of days/hours before start time. Will that be affected?
A: Yes, unfortunately that setting applies only to email, and when the PIN code is sent via Airbnb Messaging, it is sent immediately. This should still provide a good experience for your guests - they will be able to find the PIN and Access Instructions easily via Airbnb within the messages for their reservation, rather than needing to search through email.