I think I've found part of the problem with cock.li

[Shawn K. Quinn]

Host is lacking reverse DNS. I've already forwarded to Vincent.

---

This is the mail system at host mail.cock.li.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<*******@****************.com>: host
    ***.***.net[*.*.*.*] said: 450 4.7.25 Client host
    rejected: cannot find your hostname, [37.120.193.122] (in reply to
RCPT TO
    command)
-- 
Shawn K. Quinn <skquinn at rushpost.com>
http://www.rantroulette.com
http://www.skqrecordquest.com