If you require more technical detail, please refer to the follows:
DO NOT use @gmail.com, @yahoo.com, @aol.com, @hotmail.com,
@outlook.com, @163.com, @126.com, @yeah.net, @qq.com, @mail.ru in your sender address
Solution: Register a Domain
To avoid the consequences of DMARC policy changes of free email providers, use an address at your own domain. If you don’t have an email domain to use as the From email address for JSender campaigns, you can register one. Contact our support if you need further help.
Register a .com domain for HK$88/year
Friendly Link: Promotional Products Australia