I've got a couple domains I selfhost and I used Spectrum's mail.twc.com smtp server for my smarthost. I few weeks ago I noticed I couldn't send mail to my gmail using my domains and never received a bounce back with the error. Today I started getting a error finally, but it looks like I can't send out anything that doesn't match my spectrum email. Trying to figure out my best course of action that is free. I only send around 200 emails/month across all my domains. I've got a oracle free tier but this might be against their TOS. It seems my options are resend or sendgrid free tiers?

Action: failed Status: 5.1.0 Remote-MTA: dns; mail.twc.com Diagnostic-Code: smtp; 550 5.1.0 sender rejected. The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. AUP#Out-1500

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