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Every Campaign Stuck after sending 200-500 mails

I setup clean installation of phplist on linode with ubuntu 20.4 and virtualmin (New)
All test emails are going successfully. But I am getting stuck in each and every campaign with error code “554 delivery error: dd Not a valid recipient” or “550 5.7.0 Blocked - see”.
I have total 8300 subscribers.
I worked through start a new message–>process queue

Started
Processing has started,
One campaign to process.
Please leave this window open. phpList will process your queue until all messages have been sent. This may take a while
Report of processing will be sent by email

Sending in batches of 10,000 emails
and then it sits there in the web browser for hours with no change,
If I go back and view the campaign I see


(Please ignore status as I suspended this campaign just before I am writing this)

Please help me to solve this issue.

@yashwantj You should use a cron job to process the queue and use the batch settings in config.php to restrict the rate at which phplist sends emails to be within any hosting restrictions.