Why is my campaign sending slowly?

Because your campaigns are sent via your own Microsoft 365 tenant there can be various reasons for sending to be slower, such as:

• General service delays in Microsoft 365
• Throttling on your Microsoft 365 account

But more often than not campaigns with large attachments will send at a much slower rate than those without. We recommend sending attachments as links from your body (which also enables link tracking). As a guideline a campaign with 1MB attachment sends at a max rate of 30 recipients per minute (2MB at 15 per minute and 3MB at 10 per minute) but there may be other factors delaying these campaigns too!