A Customer Service Mailbox used for daily email to clients is getting blocked by Office 365 Exchange.

Sending automated emails through Office 365 via Java Mail app, the address is getting blocked in Exchange.  I then need to go to Action Center and unblock the account before I can move forward.

Sending roughly 400 email in the early AM and it gets about 300 before is sending starts failing.

What can I do to stop this account/email address from getting blocked on a daily basis?
Dan SheridanSenior System Eng / vITMAsked:
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David Johnson, CD, MVPOwnerCommented:
Use a bulk mailing service i.e. mailchimp
Office 365 has send limits

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Vasil Michev (MVP)Commented:
Using O365 in any type of bulk/marketing email scenario will only cause you troubles. You risk your entire IP range(s) getting blocked, not just the account in question. I strongly recommend you start using some of the free services that specialize in bulk emails such as MailChimp or SendGrid, instead of sending those messages via O365.
Dan SheridanSenior System Eng / vITMAuthor Commented:
Moving to a third party emailing app.
David Johnson, CD, MVPOwnerCommented:
author moving to 3rd party emailer
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