Warmup shows active, but no emails are arriving

WS
WarmySender Team
Updated Jun 7, 2026

If one of your mailboxes shows warmup as active but you've noticed that incoming warmup emails have slowed or stopped arriving, here's the short version: this is almost always a brief, temporary delivery hiccup on the receiving side — and WarmySender now detects it automatically and restores incoming warmup for you. While that's happening you'll see an "Incoming warmup catching up" note on the mailbox. Your own sending keeps working the whole time, there's nothing for you to fix, and it usually resolves on its own within a few days. This page explains why it happens and what to expect.

WarmySender is a 4-pillar outreach platform — Cold Emailing, Email Warmup, LinkedIn Outreach, and Multichannel sequences. This guide covers an Email Warmup question: why incoming warmup can briefly slow even when warmup is active.

Warmup is a two-way conversation between real inboxes

Email warmup works by having your inboxes exchange real, friendly emails with other real inboxes — sending some, receiving some, and marking them as wanted. That genuine back-and-forth is what builds your sender reputation over time, and it's why warmup is so effective: to a mailbox provider, it looks exactly like a healthy, trusted account that people are happy to hear from.

Because it's a real exchange, there are two sides to it for every mailbox: the warmup emails you send out, and the warmup emails that arrive from other inboxes. The situation this page describes only affects the second side — incoming warmup — for one of your mailboxes.

Why incoming warmup can briefly slow or stop

Since warmup uses real inboxes exchanging real emails, it's subject to the same occasional, temporary delivery hiccups that any real email can run into on the receiving side. When one of those short-lived hiccups affects one of your mailboxes, incoming warmup can briefly slow down or pause — even though your mailbox is perfectly healthy and your warmup is still marked active.

These hiccups are temporary by nature. The important part is what happens next: WarmySender is built to notice when a mailbox stops receiving incoming warmup and to restore it automatically — rather than leaving a mailbox quietly receiving nothing without anyone realizing.

A common cause: a brand-new inbox and early bounced messages

The most common time you'll notice this is in the first hour or two after connecting a brand-new inbox. Many mailbox providers temporarily hold back the very first messages arriving from senders they haven't seen before — a normal, short-lived precaution while a new inbox settles in. If a few of the early warmup messages heading to your new inbox get held back like that, WarmySender briefly pauses incoming warmup to that inbox to protect your reputation rather than keep sending into messages that aren't getting through.

When that happens you'll see the same "Incoming warmup catching up" note. Your own sending keeps working exactly as normal, this almost always clears on its own within a day or two as the new inbox settles in, and there's nothing you need to change. If the note is still there after that, reply to support and we'll double-check that inbox for you.

What the "Incoming warmup catching up" note means

When WarmySender notices that incoming warmup for a mailbox has slowed, it shows an "Incoming warmup catching up" note on that mailbox while it gets things flowing again. The note is simply there so you're never left wondering why incoming warmup looks quiet — it's a status, not an error.

So if you see the note, you can safely leave warmup running. It means the catch-up is already in progress.

There's nothing for you to fix

This is not a reconnect situation. You don't need to remove and re-add the mailbox, change any credentials, or toggle warmup off and on. Doing so won't make incoming warmup return any faster, because the slowdown isn't caused by anything on your mailbox — it's a temporary hiccup that clears on its own.

The best thing to do is simply let warmup keep running. WarmySender handles the recovery for you in the background, and incoming warmup typically returns to normal within a few days. If the "Incoming warmup catching up" note is still showing after that, that's our cue to take a closer look — see the section below on contacting support.

What it can do to your Inbox Rate (and what it doesn't)

Your Inbox Rate is measured from the warmup emails that arrive at your mailbox. So while fewer are arriving, there's a smaller sample to measure from — which can make the number look a little flat, or move around more than usual day to day. That's a side effect of the temporary slowdown, not a real change in your deliverability.

As incoming warmup returns to normal, the sample behind your Inbox Rate grows again and the number settles. The most reliable way to read it is the trend over a couple of weeks rather than any single day — especially a day when incoming warmup is still catching up. To understand exactly how the number is calculated, see Understanding your warmup Inbox Rate.

Frequently asked questions

My warmup says active but no warmup emails are coming in — is something broken?

Almost always, no. Warmup works by having your inbox exchange real emails with other real inboxes. Every now and then, one inbox can briefly stop receiving incoming warmup because of a short-lived delivery hiccup on the receiving side — the kind of temporary thing that clears on its own. WarmySender now watches for this automatically and gets incoming warmup flowing again, and while it's sorting itself out you'll see an "Incoming warmup catching up" note on that mailbox. Your warmup is still active and your own sending keeps working the whole time.

What does the "Incoming warmup catching up" note mean?

It's a heads-up that incoming warmup for that mailbox slowed for a little while and is being restored. It is not an error and it does not mean anything is wrong with your mailbox or your account. We show it so you're never left wondering why incoming warmup looks quiet — it simply means the catch-up is in progress. The note clears on its own once incoming warmup is flowing normally again, usually within a few days.

Do I need to do anything to fix it?

No. There's nothing to reconnect, no setting to change, and nothing to turn off and on. WarmySender detects the slowdown and restores incoming warmup for you automatically. The best thing you can do is simply let it keep running — it typically sorts itself out within a few days. If it's still showing after that, we'd like to take a look, so email support.

Will my own sending or my campaigns be affected?

No. This only affects incoming warmup arriving at one of your mailboxes — the warmup emails other inboxes send to you. Your own sending continues exactly as normal: your warmup keeps sending out, and your cold email and LinkedIn campaigns are completely unaffected. Nothing about your outbound activity pauses while incoming warmup is catching up.

Why does this happen at all?

Because warmup uses real inboxes exchanging real emails, it's subject to the same occasional, temporary delivery hiccups that any real email can run into on the receiving side. When that happens to one of your mailboxes, incoming warmup can briefly slow or pause. These hiccups are short-lived by nature, and WarmySender is built to notice and recover from them automatically rather than leaving a mailbox quietly receiving nothing.

I just connected a brand-new inbox and no warmup is arriving — is that the same thing?

Usually, yes — and it's expected. In the first hour or two after a brand-new inbox is connected, some providers temporarily hold back the very first messages arriving from senders they haven't seen before. If a few early warmup messages to your new inbox get held back like that, WarmySender briefly pauses incoming warmup to that inbox to protect your reputation, and shows the "Incoming warmup catching up" note. Your own sending is completely unaffected the whole time, it almost always clears on its own within a day or two as the new inbox settles in, and if it's still showing after that you can reply to support and we'll double-check that inbox for you.

How long until incoming warmup is back to normal?

In most cases incoming warmup recovers on its own within a few days. WarmySender checks regularly and restores it as soon as the temporary hiccup clears, so you don't have to watch the inbox or take any action. If you still see the "Incoming warmup catching up" note after several days, contact support and we'll check that specific mailbox for you.

Could my Inbox Rate look lower while this is happening?

It can look a little flat or move around more than usual, for a simple reason: your Inbox Rate is measured from incoming warmup emails, so while fewer are arriving there's a smaller sample to measure. That's a side effect of the temporary slowdown, not a real drop in your deliverability. As incoming warmup returns to normal, the sample grows again and the number settles. The right way to read it is the trend over a couple of weeks rather than any single day.

Still seeing it after a few days?

Incoming warmup almost always returns on its own within a few days. If the "Incoming warmup catching up" note is still showing on a mailbox after that, we'd like to check it for you. Email [email protected] with the mailbox address and we'll take a look.

Still have questions? Email [email protected] — we respond within 24 hours on business days.