Sender Blocked - Mailchannel Error

We’re receiving the following error (for every request) when sending email via workers over mailchannel:

Failed to send email: 550 5.7.1 [ESA] c. See\\u0026sender=txid=638f530978b1cba5

I’ve manually redacted the sender’s email.

Their support portal asks to create a support ticket via the hosting provider:

Has anyone faced this issue before?

1 Like

I have the same issue and I have no idea of how to fix it. I have sent a few messages to myself, first is ok, but second was blocked.

What is the error you’re receiving from the mailchannel’s end?

I am also facing this, no idea how to fix it.