Google Allo has not been updated since January last year. In December, Google announced Allo’s planned obsolescence. Allo closes today, and the e-mail application landing page now displays a goodbye message asking users to switch to Android messages. This is interesting because RCS is not widely available in the news application yet, but is getting there slowly.

Google Allo was launched in September 2016 with the email application (which was confusing because of its launch alongside Google Hangouts and the Android messenger “Messenger”) and the Google Assistant. Initially, you could only use the email application to communicate with Google Assistant, and you could speak or enter commands in the Google Assistant conversation window.

Source