have you read this :

https://www.outsystems.com/forums/discussion/65818/error-sending-email/

Hey Maria da Graça Peixoto ,

Yes I have been through this and many other solutions in forum. Still its showing authentication error.

Hi SID,

It looks like you haven't configured SMTP for send email in your environment

you can configure it in service center

Regards

Shradha

Hi SID,

Please login as administrator in service center.

Go to Administration --> Email 

Configure your SMTP details here. 

Regards,

Nilesh

Hello  S_I_D,

Could you please let me know which SMTP you are using?

If you are using Gmail smtp then you need to do the following changes.

step 1:
In your Username use your google account email and in password us the password that you have to generated in step 3

Step 2: Log-In to your google account  -

  - then go to manage your google account

  - then go to security tab 

turn on  2 -step verification  then generate the app password this is required step since 

google have disabled its less secure app feature so you have to do this way

After this you can send the emails,

Note- If this will not work the do this  one additional step - 

Go to your same account Gmail then go to the gear icon on top right 

then go to  - 

then Enable this and Apply the changes ..

I hope this will help you, if this will not work please ping

Thanks & Regards

Tousif Khan

Hi, S_I_D 

https://www.outsystems.com/forums/discussion/79316/send-email-from-outsystems-to-gmail-etc/

Hi Community,

The following issue has been resolved by doing some changes in Google's Less Secure app access. Thanks for your support.

Hi @S_I_D 

  You will go to your Gmail google setting and allow it to the less secure app.

   If your issue is resolved, then please do mark it as a solution

Thanks and regards

Ved Narayan