Is GMX email legit?

Could you please elaborate on the legitimacy of GMX emails? I've recently received several emails claiming to be from GMX, but I'm concerned about their authenticity. Some emails seem to offer investment opportunities or request personal information, which makes me wary. I'd appreciate it if you could shed some light on whether these emails are genuine or if they're part of a scam. I'm particularly interested in knowing if GMX has an official email domain and any security measures they recommend for identifying legitimate communications. Thank you for your assistance in this matter.