If you encounter problems in which you are not able to send out emails but can receive them, this could be due to your email application does not have Outgoing Server (SMTP) Authentication enabled. Below are the two most used email clients that encounter such errors.
1. Open Outlook.
2. Click File tab.
3. Choose Account Settings, and click Account Settings... again.
4. Select the email address you’re having troubles with and click Change.
5. On the Change Email Account screen, click More Settings… button.
6. Choose Outgoing Server tab, and make sure that My outgoing server (SMTP) requires authentication is ticked.
6. Click OK, and then click Next.
This will verify the settings and once you get two ticks for incoming and outgoing server settings, you’re good to go.
1. Open Thunderbird.
2. Right-click on the email address you are having troubles with and choose Settings.
3. On the Account Settings screen, click on Outgoing Server (SMTP).
4. Select the email that you are having troubles with and click on Edit button on the right.
5. Ensure that your email address is correct on the User Name field.
6. Click OK. Lastly, click OK on the Account Settings screen.
Once this is all done, try sending out an email again to test.
If you have any other settings, you’d like to do changes with click on the guided link on more information about how to edit email server settings.