The use of a more secured methodology (e.g. OAuth2.0) means that more network overheads are introduced. For an SMS received, you will be redirected to your Gmail account to key in your password to exchange for a token. It is more secured because this token, rather than your password, is stored in the phone. The app then uses it to access your sender Gmail account to send out the email. Subsequent accesses can be performed until the token expires and the app repeats the process to acquire a new token. This severely affects the functionality of our apps to perform efficient SMS forwarding. Hence in the meantime, until we can incorporate this authentication mechanism without sacrificing efficiency, you may be required to specify the settings to 'allow less secure apps access' in your sender Gmail account.
However, we encourage you to follow these recommendations when using these apps to minimise your risks:
If you have any queries, please drop us a line.