You opened your account this morning and your campaign sent zero emails overnight. Yesterday it was sending fine. But, nothing changed on your end and the campaign status says active. The leads are still in there but nothing is going out.
This happens more than people realise. The good news is the reasons are almost always one of seven things, and most of them are quick to fix once you know which one it is. Here is what to check, in the order you should check them.
Probably, yes. A silently disconnected mailbox is the number one reason by a wide margin, and Gmail OAuth tokens are the usual culprit. Google quietly expires the authentication every so often, and unless you reconnect, your campaign cannot send. Outlook does this too, just less often. SMTP credentials can break if you change a password.
The frustrating part is that the campaign still looks active. Nothing flashes red and the emails just queue up and never go.
When you ask SmartAssistant why your campaign stopped, it pulls your mailbox status first. A typical answer looks like, "Your campaign 'March Outreach' has sent 0 emails in the last 24 hours. Two of your three connected email accounts are disconnected because Gmail OAuth tokens expired. Reconnect them via Google OAuth and the campaign will resume." Then it navigates and takes you to the Email Accounts page, so you don't have to figure it out.
If you are seeing zero sends, check this first. Just ask your personal AI assistant and it takes care of it for you.
Every mailbox has a daily sending cap that you set when you connected the mailbox. Most senders keep it between 30 and 50 cold emails a day per mailbox to protect deliverability. If your campaign needs to send more than your cap allows, the rest sits in queue until tomorrow.
This is not really a bug, it is the tool protecting you. But it does mean that if you have one mailbox sending to a 500 person list, you are looking at 10 to 15 days of sends. Not a problem with the campaign, just a math problem.
Smartlead's cold email AI assistant can pull your daily limits across all connected mailboxes and tell you the realistic timeline for any campaign. If the limit is the bottleneck, it can also suggest connecting more mailboxes to scale.
It might be because campaigns get paused for a few reasons.
The campaign status in your account will tell you the truth here. If it says paused, that is your answer. SmartAssistant can also check this and tell you when it was paused, who paused it, and whether it is safe to resume.
If your mailbox is in active warmup, the tool will protect it by not sending too many cold emails on top of the warmup volume. This is a feature, not a bug. The warmup is building the reputation that lets your cold emails inbox later. If you push hard sending volume during warmup, you can undo weeks of work in a day.
SmartAssistant checks warmup status as part of any campaign diagnostic. If it sees you have only been warming for six days, it will tell you to wait or to reduce the daily cold sending limit until warmup is further along.
Possibly, your campaign has a sending window, say 9am to 5pm in a specific timezone. If you set it up in your timezone but your campaign is scheduled in a different one, you might not have any active sending hours overlapping when you expected. The campaign sits and waits.
This is most common when people connect a campaign during evening hours and check it the next morning, expecting sends overnight that never happened because the window was closed.
Ask SmartAssistant when the next send is scheduled and it will tell you the next active window for the campaign, in your timezone.
Sometimes that is what is going on. The campaign is fine, but there are no leads left to send to. Maybe everyone already received the last step in the sequence. Maybe a bounce cleanup removed leads. Maybe a filter excluded the leads you thought were active.
SmartAssistant can tell you exactly how many leads are queued, how many have already received the current step, and whether any rule is filtering them out.
Smartlead watches for trouble signs like sudden bounce spikes, complaint rates, or reputation drops. If something looks bad, the campaign auto pauses to protect your domain. This is rare but it is the cause most people miss because they assume their campaign is fine.
The fix is not to just resume, because the underlying problem will still be there. SmartAssistant will tell you what triggered the auto pause and walk you through fixing the cause before restarting sends.
Instead of clicking through seven different pages to check each of these, you open the chat panel and type, "my campaign stopped sending, what's wrong." The assistant pulls your campaign status, mailbox connection status, sending limits, warmup status, sending window, lead count, and recent bounce data in one go. It comes back with the specific reason in your account and the fix.
For most people the reason is reason number one, the silently disconnected mailbox. For everyone else it is one of the other six, and the assistant tells you which one.
The most common cause by far is a disconnected mailbox, usually Gmail OAuth that quietly expired. Check that first. If your mailboxes are connected, check daily sending limits, sending hours, and warmup status. SmartAssistant can check all of these in one diagnostic.
Active just means the campaign itself is on. It does not mean sends are happening. The most likely cause is that the mailboxes attached to the campaign are disconnected or out of sending capacity for the day. Open the chat panel and ask the assistant to run a campaign diagnostic.
There is no fixed schedule. Google can revoke the token for security reasons, inactivity, password changes, or just because. The result is that you should expect to reconnect Gmail every few weeks on average. SmartAssistant flags this the moment it happens so your campaigns do not silently stall.
It can resume a paused campaign once you confirm. It will not restart a campaign that is auto paused for a deliverability reason without walking you through the cause first, because that protects your domain from a bigger problem.
Most experienced senders keep each mailbox between 30 and 50 cold emails a day, and add more mailboxes when they need to scale volume. SmartAssistant can tell you what your specific account is ready for based on warmup and history.
Usually a sudden spike in bounce rate or a complaint signal that crossed a safety threshold. The assistant can tell you exactly what triggered the pause and what to fix before resuming.
Yes, the assistant works inside your Smartlead account. It's a personal AI assistant that knows your account. If you are evaluating tools, you can sign up free and have the assistant walk you through the setup before sending a single campaign.
If a campaign of yours is sitting at zero sends right now, open the chat panel and ask the assistant what stopped it. If you are not on Smartlead yet, sign up free and let it set up your first campaign without the usual breakage.
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Founder, StackOptimise
Smartlead's combination of automation, unlimited inboxes, and easy campaign management has completely transformed how we run cold email campaigns.
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Founder, Cold Email Hackers
We have about 15 companies and we use Smartlead for all of them.
Founder, DutchSave Media
One of the things I love about using Smartlead is the deliverability feature. If they landed in the bounce or spam folders, we could resolve this quickly.
Co-Founder, Growth Today
I want to continue to use Smartlead to make operations more seamless - the plan is to bring more clients here and build more SOPs.
Founder, FueltoFly
Smartlead listens to the agencies and customers and builds according to what people want, that has really made things easier for us.
Founder, OutboundSync
We build an infrastructure product, and OutboundSync communicates with Smartlead itself. I love the webhook and API. They're really well done and keep getting better.
Founder, Axoleads
With SmartDelivery, you can put all of that in the hands of the tool. It ensures your emails land in inboxes, and by running a simple test, you can see if you're hitting the mark.
Founder, Claygen
Deliverability is the cornerstone of cold email outreach. You could have the best email copy in the world, but if no one is seeing it, it's useless. I really love the feature where you can actually give client accesses to your clients.
Co-Founder, Cymate
I do not want to switch to another software. Pick a solution you trust, stick with it, and keep refining your copy.
CMO, Avalanche Capital
Managing large volumes of emails through multiple inboxes used to be a logistical nightmare. With Smartlead, the process is seamless. We book thousands of discovery calls through cold emails. These campaigns are generating leads at a scale we never thought possible.
Founder, Growth Engine X
We came for the unlimited inboxes, and we stayed for the API. 1.5M cold emails/month, 7,767+ inboxes managed.
Head of Community & Ecosystem, TxtCart
You cannot replace having 10,000 touches with potential clients. When you have that much distribution and reach, you really start to see incredible results. The simplicity of Smartlead made all the difference. It doesn't require you to be a technical wizard.
Founder, Hyperke
Smartlead has been a game-changer for us. It increased our appointment volume, improved ease of use, and offered valuable features. 80% increase in appointments/month, peak of 276 appointments in a single month.
Founder, Kinetyca
Smartlead has been our cold email backbone from day one. The platform evolves constantly, keeping pace with how deliverability and personalization need to work today. 21% overall reply rate, $175K in 4 months for multiple B2B clients.
Founder, Reachflow
Smartlead is centered around deliverability and constantly evolving. Their API is not like any other platform. Smartlead covers all our needs. The focus on core features like deliverability and API integration is unmatched.
CEO, Halfwarm
Our approach to crafting conversational emails led to reply rates that many of my peers thought were unattainable.
Co-Founder, letstrike
We've grown on zero capital, zero marketing, purely cold emailing - and that's the story we love to tell. The best approach is no approach if you can't handle domain meltdown. The second best is something like Smartlead that's built from the ground up for deliverability at scale.
Founder, Fenixtal
Smartlead's white-labeling and automation let us punch above our weight. The 12M euros sales potential? That's what happens when you combine human creativity with Smartlead's precision.
Co-Founder, Digital Creativs
Nine out of 10. Ninety percent of our clients are on Smartlead unless they come in with an existing setup. That's the default.
Co-Founder, BuildingReach
At the end of the day, you have to take a bet on one tool or another. It was a no-brainer taking that bet on Smartlead. We had to even turn down the volume of our marketing campaigns - Smartlead was capable of driving more volume than our sales team was able to fulfill.
Founder & MD, Prospectiv
Since starting the business in January of this year, we've already generated $200K in sales exclusively from cold email. Smartlead has been central to our operations and has exceeded our expectations.
Founder, Growthlynk
There's so much stuff built on top of it. I would be dead if I had to rebuild it with another tool. I can manage hundreds of senders easily. I can send hundreds of thousands of emails.
Founder, Corebits
The platform's HubSpot integration, real-time Slack updates, and advanced campaign customization have been game changers for our business and our clients'.
Founder, Apex Ascension
From day one, we've never used anything else.
