Alternative way to send email without getting "Suspicious sign in prevented"

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http://stackoverflow.com – Is there any free way to send email from an app, without getting "Suspicious sign in prevented"? Currently, I'm creating a dummy GMail account, to send email from my app using the following described way : http://stackoverflow.com/a/3649148/72437 However, once in a while, due to heavy usage by my app users from different location, certain message will fail to send. I get the following message from Google : Hi xxx, Someone recently tried to use an application to sign in to your Google Account - [email protected] We prevented the sign-in attempt in case this was a hijacker tryi (HowTos)