Live queue depth
See how many messages are waiting per destination domain — with recipient counts, size, active connections, and mode — as the live state of your outbound, not a stale snapshot. A top-queues view ranks where volume is piling up.
Insights
See exactly what's waiting to send.
For high-volume senders, throughput is operational. Queue Management shows what's queued, retrying, and stuck — live depth per destination domain and Pool, with the controls to act when a queue won't drain.
queues · live
DomainPoolRcpt
gmail.com acme-promotional 8,705
outlook.com acme-promotional 5,130
yahoo.com acme-transactional 2,637
gmail.com acme-drippaused 1,264
Top queues
gmail.com
outlook.com
yahoo.com
gmail.com
per domain × poolflush available
What it gives you
Depth, attribution, control.
Broken down by infrastructure
Queues are organized by recipient domain and the Pool handling them, so you can tell whether a backlog is a Gmail-wide throttle or specific to one of your Pools — and act accordingly.
Control when you need it
Most backlogs clear on their own via retries. For the rare genuinely-stuck queue, a flush clears it deliberately — an operational lever for when draining beats endlessly retrying a hopeless destination.
Why it matters at scale
When you send millions, throughput is a metric.
At low volume, mail just sends. At millions, sending becomes a flow you manage: a receiving ISP throttles you, a domain starts deferring, a queue backs up. Without visibility, the first sign is a delivery report that looks slow hours later. With it, you watch the backlog form and know immediately which destination and which Pool is the bottleneck.
The top-queues ranking is the fast diagnosis: when throughput dips, the queue piling up at the top tells you where to look — a specific ISP throttling, or one Pool's IPs being treated differently. Most of the time retries clear it; the flush control is there for the genuinely stuck.
What it removes
The blind spots of high-volume sending.
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No idea why throughput dipped
A slow send with no queue view is a mystery until the report lands. Live depth shows the backlog forming and where, in real time.
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Can't tell ISP throttle from your problem
Is Gmail throttling everyone, or is one Pool the issue? Per-domain-by-Pool queues answer it at a glance.
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A stuck queue retrying forever
A hopeless destination shouldn't tie up capacity indefinitely. A deliberate flush clears it when draining is the right call.
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Throughput invisible until reporting
Discovering a slowdown hours later in a report is too late. Queue depth is the live operational view senders at scale need.
What it tells you at scale
The diagnoses a queue view makes obvious.
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A backlog forming
- What you see
- One domain's queue depth climbs while others stay flat.
- What it means
- That ISP is throttling — you know to slow that lane or wait it out, instead of guessing why throughput dipped.
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ISP throttle vs your problem
- What you see
- A domain backs up across every Pool — or just one.
- What it means
- Across all Pools points to an ISP-wide throttle; one Pool points to that Pool's IPs being treated differently. The breakdown answers it instantly.
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A genuinely stuck queue
- What you see
- A destination keeps deferring and won't drain.
- What it means
- Flush it deliberately rather than tying up capacity retrying a hopeless target — an operational lever, used sparingly.
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A big send in flight
- What you see
- Millions are going out and you need to know it's flowing.
- What it means
- Watch the top-queues ranking drain in real time, so you catch a slowdown as it starts rather than in a report hours later.
“When you send at our volume, "it'll send eventually" isn't good enough — you need to see the flow. The per-domain-by-Pool view is exactly that. Last month Gmail started deferring one Pool and we saw the queue climb in real time, isolated it to that Pool's IPs, and acted before it touched the rest.”
Verified review
Mumara ONE customer
G2
Common questions
What buyers usually ask.
What does Queue Management show?
Live queue depth per destination domain — recipient counts, size, active connections, and mode — organized by the Pool handling each queue, plus a top-queues ranking of where volume is concentrated. It's the real-time state of your outbound, not a snapshot.
How are queues organized?
By recipient domain and the Pool sending to it. That breakdown lets you distinguish an ISP-wide throttle (one domain backing up across Pools) from a Pool-specific issue (one Pool's IPs being treated differently).
Can I clear a stuck queue?
Yes. Most backlogs clear themselves through retries, but for a genuinely stuck queue you can flush it deliberately — clearing it rather than continuing to retry a destination that won't accept the mail.
Who needs this?
Primarily high-volume senders, where throughput is an operational concern. If you send millions, watching queue depth is how you catch and diagnose slowdowns the moment they start instead of after the fact.
Related
Pages that pair with this one.
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IP Pools
Queues are organized by the Pool sending to each domain — diagnose per-Pool throughput.
Read more -
Realtime Delivery Status
When a queue drains, delivery and deferral events show up in the live DSN stream.
Read more -
Dashboard
The at-a-glance screen you drop into queue depth from when throughput looks off.
Read more -
Reputation Monitoring
Deferrals and throttling often track reputation — rules can throttle proactively.
Read more
Mumara ONE · Queue Management
Watch the flow, not just the report.
Live queue depth per domain and Pool, a top-queues ranking to find the bottleneck fast, and a flush control for the stuck ones — the operational view for sending at scale.