In AutoResponder, depending on the use case, there are two ways to send a welcome message when a message is received.
Use the Welcome Message option as described in the article you are just reading. This will automatically reply only to the very first message from a contact previously unknown to AutoResponder to welcome them to the chat.
To reply with recurring welcome messages, which can also be sent to existing contacts, you can use the All button in combination with the Pause rule for… option as described under the Greeting Messages headline of this article.
Using the Welcome Message option in AutoResponder
The Welcome Message option is located in the Received Message section within a rule.
Just select it and finish the rule. AutoResponder will then reply to the very first message (since AutoResponder is installed and running) from an unknown contact. If a message has already been received from this contact, no reply will be sent.
If you want to include groups in the Welcome Message rule, a message will be sent when you are added to a new group. It is not possible to welcome other new group participants automatically.
Note: In AutoResponder for WhatsApp, Welcome Messages are sent to contacts not saved in your contact list only.
If you want to send recurring welcome messages or you want AutoResponder to include existing contacts as well, please use Greeting Messages.