Microsoft 365 (bulk) Sending Limits (and How to Send More)

Hitting Microsoft 365 (bulk) sending limits? Here is what they are and how to scale past them.

Microsoft 365 (bulk) limits

For bulk email Microsoft recommends a dedicated sending service, since mailbox limits and throttling block campaigns.

How to send more

• Move to a dedicated sending domain and IP.
• Authenticate fully and warm up gradually.
• Segment and keep complaints low.

How Rainmail helps

Rainmail sends from your own domain on a dedicated, isolated IP with SPF, DKIM, DMARC, reverse-DNS and managed warm-up handled for you, a REST API, and an AI watching deliverability — and it welcomes senders SES, SendGrid and Mailchimp reject, from $8. Run the free checker or see plans.