Has China Mobile or China Unicom got email outgoing server ?
When I am in China and use China SIM-card, I have a problem sending mails. Receiving is Ok!
The outgoing server I use in Denmark is my Phone and internet provider, “mail.Telenor.dk” please confirm me the outgoing server in Chine for my SIM-card.
China Mobile and China Unicom have no outgoing server to customers. In theory, your current Denmark outgoing mail server should work in anywhere in the world. Chinese government blocked some servers. Unfortunately, it may wrongly include your one.
Try changing your outgoing SMTP port to 26. It's usually defaulted to port 25 (which may be blocked by local ISP).
You may use SMTP2Go Worldwide SMTP Server to send emails from any locations in the world.
Other suggestions are:
1. To use VPN For Proxy to bypass blocked server in China
2. To try another mail server/mail box, for instance, yahoo