Estou recendo esse seguinte erro aonde tentar enviar um email:
This is the mail system at host UBMSA01.spo2.umbler.com.
I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
pauloh.gamer@gmail.com: host aspamout01.umbler.com[187.84.237.181] said: 553
5.1.8 pauloh.gamer@gmail.com… Domain of sender address
contato@billet.com.br does not exist (in reply to RCPT TO command)