Any way to send emails without getting banned as like Gmail.?

Hello yesterday I sent around 400-500emails with a free Gmail account.
But it survived and I got some replies for 24 - 36hours after it it got banned.
I think my recepients marked it as spam and my email is banned. I cannot login to it anymore.
Now my query is is there any way to send like 25k emails I don't care if it lands on spam folder or inbox but I should not be banned.
Is there any turnaround?

If you don't care about Spam/Inbox, build your own sender in PHP, and use a VPS.

Not with Gmail. To send large quantities of email, try Amazon SES.

Clickback mail is the ultimate tool if you want to send out bulk cold email messages without being blacklisted or landing in your recipients’ junk folders.

did you use bcc/cc to email more then 1 person at once?