Around two minutes and six seconds. That is how long it takes ContactMonkey to send an email to 150,000 recipients.
If you have ever managed internal communications at a large organization, you already understand why that number matters. A company-wide send is rarely a routine task. It is a town hall announcement, a crisis update, a CEO message, a policy change that employees need to act on before end of day. The message going out is only half the job. The other half is making sure it actually arrives, and arrives now, not in waves over the next thirty minutes while some employees get the news from Slack before they ever open their inbox.
Speed in internal email is an operational metric, not a vanity one. And ContactMonkey just raised the bar.
Why Internal Email Delivery Has Always Been a Bottleneck
Most internal communicators do not spend much time thinking about what happens after they hit send. That is by design. The technical infrastructure sitting behind your email tool is supposed to be invisible.
But the limits of that infrastructure have a way of making themselves known. You schedule a send for 9:00 AM and by 9:45 AM you are still fielding questions from employees who have not received it yet. You send an urgent safety communication and spend the next hour manually checking whether it has reached everyone on the list. You run a campaign and your open rate data trickles in unevenly because the email did not land simultaneously across your audience.
These are not edge cases. For organizations sending to thousands or tens of thousands of employees, staggered delivery is the norm. The traditional infrastructure powering most internal email tools was built for a different era of communication, one where speed mattered less than it does today.
Native Outlook delivery, which has been the backbone of many internal email platforms, moves at roughly 30 emails per minute. At that rate, a send to 150,000 employees would take the better part of three and a half days to complete. Even more recent approaches to scaling email delivery topped out around 450 emails per minute, which still means hours of delivery time for enterprise-scale audiences.
ContactMonkey has rebuilt this from the ground up.
Introducing SendGrid-Powered Sending
ContactMonkey delivers email through SendGrid infrastructure, and the throughput difference is transformational.
The new sending engine runs at 75,000 emails per minute. Compared to the previous standard of 30 emails per minute through Native Outlook, that is a 2,500x improvement in send speed. Compared to earlier scaling approaches, it is 167 times faster. The result is that a 150,000-recipient send, which previously would have taken hours or days to fully land, now completes in around two minutes and six seconds.
That kind of speed changes what internal email can do. It means that when something urgent happens, your message reaches everyone at the same time. It means your open rate data reflects a real simultaneous moment, not a rolling window of delivery. It means the gap between when you send and when employees know is almost nothing.
What This Means in Practice
For most ContactMonkey customers, this upgrade is seamless. There is nothing to configure, no migration required, and no change to how you build or send emails. The speed improvement happens automatically at the infrastructure level.
There is one scenario worth noting for IT teams. If your organization has email throttling rules configured on the receiving side, your IT administrators may want to review those settings. Organizations that have set strict inbound rate limits could see some interaction with the higher delivery speed. This is more relevant for smaller environments with conservative throttling configurations than for large enterprise deployments, and your ContactMonkey customer success manager can walk you through any specific considerations for your setup.
For communicators, the practical impact is straightforward. Time-sensitive sends are now genuinely time-sensitive. Emergency communications reach your full workforce in minutes, not hours. Planned campaigns land simultaneously, which means cleaner data and a more consistent employee experience from the moment the email arrives.
The Bigger Picture
Internal communicators have spent years advocating for a seat at the leadership table, arguing that the work they do has direct impact on business outcomes. That argument gets a lot easier to make when your tools perform at the level your work demands.
ContactMonkey has always believed that internal email deserves the same quality of infrastructure as the best external marketing tools. The move to SendGrid delivery is the most direct expression of that belief yet. It brings enterprise-grade sending speed to internal communications, eliminating one of the oldest and most persistent limitations of the channel.
About two minutes and six seconds for 150,000 recipients. The next time something important happens at your organization, your employees will know about it before they have a chance to wonder.
Your employees shouldn’t be the last to know. Book a demo and see how ContactMonkey gets your most important messages delivered in minutes, not hours.
