I'm not able to send a message to a certain User ID via the API

Instagram generates specific User ID for each customer that reaches out to you. The User ID for each customer differs per channel. If you try to reach out to a User ID via a different channel then where this was generated, your message will not reach the customer. Let's look at an example below:

I own two different brands, Brand A and Brand B, and have a different Instagram channels set up for each brand. John is my customer and likes to shop at both brands.

• John has reached out to me via the Brand A Instagram channel, where his User ID was generated as 123456789.

• The same John reached out regarding a question to the Brand B Instagram channel, but this time his User ID was generated as 444444444.

When submitting your API request, you will need to submit both a to and from parameter. The to parameter will contain the channel-specific identifier (123456789 & 444444444 in the examples above) or a MessageBird Contact ID. The from parameter will contain the ID that identifies the channel the message should be sent over. Make sure that, if you are entering a channel-specific identifier, you are entering details that match the right channel.