Gmail blocking my mail server again and again

[SK MD JABIR]

host gmail-smtp-in.l.google.com [142.250.110.27]
SMTP error from remote mail server after end of data:
550-5.7.1 [51.17*.27.** **] Our system has detected that this message is
550-5.7.1 likely suspicious due to the very low reputation of the sending IP
550-5.7.1 address. To best protect our users from spam, the message has been
550-5.7.1 blocked. Please visit
550 5.7.1 Why has Gmail blocked my messages? - Gmail Help for more information. b10-20020adfe30a000000b00207a5abd32fsi7040480wrj.1005 - gsmtp


The bounce rate was 0% for sure. per email was sent 175 seconds later. In only 2 days only 1000 email has sent. I'm confused about why! Warmup is not working. Changing the domain is work.

 

[T J Tutor]

My guess is that you have been added to some of the blacklists out there.

Per Google:

Why has Gmail blocked my messages?​

Troubleshoot delivery issues with Postmaster Tools
Gmail Postmaster Tools provides senders with metrics on parameters such as reputation, spam rate, feedback loop, etc. It can help you prevent your emails from being blocked or sent to spam by Gmail.
Here at Gmail, we work very hard to fight spam. While in some cases we may classify a message as spam and deliver it to the spam folder, we also try to find ways to reduce the amount of spam being sent to Gmail in general. If we detect that a message has a strong likelihood of being spam, we’ll block the message from being sent to Gmail.
A message might be blocked if it contains suspicious-looking or spammy text or if the sending IP has had a history of sending unsolicited messages.
Is all of the mail I’m sending being blocked?
It’s likely that only a subset of the messages which have a strong likelihood of being spam are being blocked and not all of your messages. However, to help improve your deliverability, we recommend reviewing our Bulk Sender Guidelines.
If you’re forwarding mail to Gmail and your domain also forwards spam, we recommend reviewing our mail forwarding best practices.

 

[Graybeard]

Welcome to SPAM Jail --You're busted

Why has Gmail blocked my messages? - Gmail Help

Troubleshoot delivery issues with Postmaster Tools Gmail Postmaster Tools provides senders with metrics on parameters such as reputation, spam rate, feedback loop, etc. It can help you prevent your em

support.google.com

What is your mail list source?
What is your subject and body content?
Your send rate is speciously high --too obvious.