To safeguard your long-term email deliverability, MAAC includes an automated deliverability-protection mechanism. The system continuously monitors the sending health of your sending domain and automatically adjusts the sending speed of your Email Broadcasts, so you can focus on your marketing content without manually managing sender reputation or bounce rates.
This article explains how the Sending Governor, domain health status, daily sending capacity, and the sending queue work.
The automatic throttling and daily sending limits described in this article apply only to Broadcasts. Emails in a Customer Journey are real-time, time-sensitive messages; they are not blocked by sending limits and are prioritized for delivery.
Sending Governor
Every email sent through MAAC passes through the system's Sending Governor. It evaluates your sending domain's deliverability quality in real time and automatically controls the sending speed of broadcasts accordingly, to avoid harming your domain reputation through large bursts of sending or poor sending quality.
Because broadcast traffic and Customer Journey traffic are isolated from each other within the system, sending a large broadcast at once will not delay the more time-sensitive notification messages in your Customer Journeys.
Domain Health Status
Based on your sending domain's recent bounce rate (hard bounce) and spam complaint rate (Complaint—the rate at which recipients mark your email as spam), the system automatically determines your domain's health status and applies different sending behavior. The trigger conditions and sending rate for each status are as follows:
| Domain Health Status | Trigger Condition (recent sending data) | Broadcast | Customer Journey |
|---|---|---|---|
| Building Reputation | Newly enabled, or a domain that hasn't sent for over 30 days (auto warm-up in progress) | Sends normally; sending volume increases gradually as warm-up progresses | Not affected |
| Healthy | Bounces < 2% and complaints < 0.1% | 100% rate | Not affected |
| Warning | Bounces ≥ 2% or complaints ≥ 0.1% | Throttled to 50% rate (still sending) | Not affected |
| Restricted | Bounces ≥ 5% or complaints ≥ 0.3% | Throttled to 20% rate (still sending) | Not affected |
| Suspended | Complaints ≥ 0.8%, or a sending-policy violation | Paused immediately (0%) | Paused as well |
*The system begins evaluating health status only after at least 200 emails have been sent; Admin Center shows the hard bounce rate and spam complaint rate over the last 24 hours for your reference. Bounce = hard bounce; complaint = spam complaint.
Warning and Restricted only "automatically slow down Broadcast sending" while sending continues, and they do not affect Customer Journeys—no manual action is needed; once the metrics fall back below the thresholds, the rate recovers automatically.
However, once a domain enters Suspended, both Broadcasts and Customer Journeys are paused entirely, and a CSM must review and restore the domain before you can send again.
Status Change Notifications
When your domain health status deteriorates, the system notifies you through in-app notifications and email reminders, and shows a warning banner on the Broadcast page explaining how your sending may be affected.
Daily Sending Capacity and the Sending Queue
Each sending domain has a daily sending capacity (Daily Capacity) limit that controls how many broadcast emails go out in a single day, preventing sudden volume spikes from harming your domain reputation. The daily sending capacity adjusts automatically based on your domain health and sending performance.
The daily sending capacity counts only Broadcast volume; Customer Journey emails are not blocked by the daily sending capacity and are sent as usual. You can view today's used and remaining capacity in the Email channel settings in Admin Center. 👉 To learn how, see: Onboarding Guide | How to Enable Email Channels and Import Contacts
When a broadcast's recipient count exceeds the available capacity for the day:
- The broadcast is still accepted by the system and is not marked as failed.
- The portion that can be sent that day goes out first, and the remaining contacts are automatically queued.
- Queued emails resume automatically the next day at 09:00 (in the time zone configured for your account), until they have all been sent.
When a sending domain reaches its daily sending limit, a prompt appears at the top of the Broadcast page, for example:
"{domain} has reached today's sending limit. Email will resume after 09:00 the next day (in the time zone configured for your account). Need to send urgently? Contact support."
Broadcasts created or scheduled at this point are still accepted and queued, and begin sending automatically the next day.
If you have a time-sensitive, high-volume campaign that needs a higher daily sending capacity, contact your CSM to request an increase. Note: capacity-increase requests apply only to sending domains in the "Healthy" status, and each increase can raise capacity to at most 2× the original. Domains in warm-up (Building Reputation) cannot have their capacity increased manually.
Pre-Send Compliance Check
To protect the sending IPs shared by all customers, the system checks your sending domain's status before sending or scheduling. If the domain status is Suspended or Not Set, the "Prepare to send" / "Schedule" buttons are disabled, with guidance links to Admin Center and the documentation.
In addition, a scheduled broadcast is checked once more before its actual send time. If the domain is Suspended at that point, the broadcast does not run; its status is marked as "Paused (risk protection)", and an in-app notification and email reminder are triggered.
Automatic Warm-up (Reputation Building)
For newly enabled sending domains, or domains that haven't sent for a long time, the system automatically enters the "Building Reputation" status and gradually increases the daily sending capacity to build sending reputation—fully automatic, with no need to manually arrange a traditional IP warm-up schedule. During warm-up you can still create and send broadcasts as usual; anything beyond the day's safe sending volume is automatically queued and continues later that day or the next day.
👉 For full details, see: Feature Description | Email Automatic Warm-up (Reputation Building)
FAQs
Q: I didn't change anything, so why did my broadcast slow down?
This usually means your sending domain has entered the "Warning" or "Restricted" status, and the system automatically reduced the speed to protect your domain reputation. Sending still continues, and no manual action is needed; we recommend reviewing the quality of your recent content and contact lists to improve your bounce and complaint rates.
Q: How do I recover after my domain is Suspended?
Suspension means sending quality has seriously damaged your reputation. The system automatically resumes the previously paused broadcasts once your domain's sending quality returns to healthy. We recommend cleaning your list and removing invalid or unengaged contacts before sending again. Contact your CSM if you need help.
Q: Will my broadcast fail after I reach the daily sending limit?
No. Contacts beyond the day's sending capacity are automatically queued and resume the next day at 09:00 (in the time zone configured for your account); they are not marked as failed. If you have an urgent send, contact support.
Q: Are Customer Journey emails also throttled or queued?
No. Automatic throttling and daily sending capacity apply only to Broadcasts; Customer Journey emails are prioritized and unaffected. The only exception is when a domain enters "Suspended": both Broadcasts and Customer Journeys are paused together until the domain recovers.
Q: Can I increase my daily sending capacity?
During warm-up (Building Reputation), capacity increases automatically based on usage and cannot be raised manually. Once your domain reaches the Healthy status, you can contact your CSM to request a capacity increase for time-sensitive, high-volume campaigns (up to 2× the original per increase).
Q: I haven't sent for a while—why did my sending capacity drop?
When a domain stays at low usage for a long time, the daily sending capacity gradually converges based on past sending. If there is no sending at all for 30 consecutive days (counting both Broadcasts and Customer Journeys), the domain re-enters "Building Reputation" and warms up again from a more conservative capacity. We recommend maintaining a reasonable level of sending even in the off-season to avoid a reset.
Q: What happens to a scheduled broadcast if the domain is Suspended before the send time?
The system checks your domain health status again at the scheduled send time. If the domain is Suspended at that point, the broadcast does not run; its status is marked as "Paused (risk protection)", and an in-app notification and email reminder are sent.
📚 Further reading: