Hello
The bounce back email was cut off so I can't see the exact error code, etc.
But based on most common issue I've seen, the issue is rich/plain text vs. html format issue. The bad news is, on the phone, there's no way to turn off html format, which is by default.
But if you have access to computer, try this:
Can you use the instruction here, change the email to plain text or rich text format (basically avoid the html format) and see if it goes through: