Why warm-up turns itself off (and how to restart it)
When warm-up stops without you touching it, it is almost always a safeguard, not a bug: Emelia stops it as soon as it can no longer run properly, to protect your mailbox and the warm-up network. The good news is that the cause is written in black and white in Emelia.
How to spot it
Emelia does not send you an alert when warm-up stops. The sign is the switch in the Warmup column, on the Accounts page: it is back on the snowflake, and a small clock icon has appeared to its left.
Click that clock: the Warmup history summary shows the last health score and the date of the last activity. The View history button opens the detailed window, with the Paused badge and, just under the title, the reason for the stop in red. That is the message to read first: it almost always tells you what to do.
When the mailbox's connection drops, the Status column shows Disconnected with a Reconnect button, and the dashboard lists it under Action Required. A reconnection email may also be sent to the address you use to log in to Emelia (not to the mailbox itself): check your junk folder.
The causes, and how to fix them
Here are the causes we come across, from the most common to the rarest, with the start of the message you will see in red in the detailed window.
The mailbox got disconnected
Message: We could not sign in to your mailbox with its current settings… Emelia can no longer log in to the mailbox: password changed, two-factor authentication enforced, Google or Microsoft licence expired, app password revoked, or a temporary refusal from the host.
Fix the connection with the Reconnect button in the Status column, then turn warm-up back on: it does not restart by itself after a reconnection. A campaign using that mailbox also refuses to start while it is disconnected.
We have seen OVH mailboxes disconnect although nothing had changed: simply reconnecting with the same credentials was enough. On OVH's Zimbra offer, an anti-spam block also cuts the connection; it shows in the OVH customer area and is lifted through OVH support.
Your sending server rejects warm-up emails
Messages: Your email server rejected … warmup emails as spam… or Your provider doesn't support our system… Your own host's anti-spam filter is blocking the emails, often because it spots automated sending. It is not an Emelia setting.
Before blaming the host, check your SPF and DMARC: an SPF left pointing at a former host has caused this very message before. But some hosts block warm-up whatever you do. From what we see, it does not hold for long at Infomaniak, Hostinger, Gandi or LWS, nor on consumer internet provider addresses (such as SFR, Orange or Free in France). With o2switch, Emelia even refuses to turn it on: “Your email provider doesn't support our warmup system, it cannot be activated.”
You can try turning it back on after checking your DNS. If the stop comes back, the only lasting fix is to move your sending mailboxes to Google Workspace or Microsoft 365, on a domain dedicated to outreach: your website and main address can stay where they are. See buying dedicated domains and mailboxes.
Too many warm-up emails bounce
Message: Many of emails we sent to different addresses end up rejected… More than 30% of the warm-up emails the mailbox sent that day came back as errors. Usual causes: a DMARC policy that is too strict (p=reject or p=quarantine), a host sending limit exceeded, an address on a blocklist, or a brand-new Microsoft 365 tenant (see just below).
Fix the cause, switch your DMARC back to p=none if needed (the exact value), then turn warm-up back on.
Microsoft 365: error 550 5.7.708
Bounce or message: 550 5.7.708 Access denied, traffic not accepted from this IP. It hits recent Microsoft 365 tenants, on trial or just paid for: Microsoft considers the sending IP address to have too low a reputation. It is not Emelia's IP: a mailbox connected through the Microsoft connection sends via Microsoft's servers. Outlook may even keep sending normally in the meantime.
- Check in the Microsoft 365 admin center that the subscription is no longer a trial and that every mailbox has its licence assigned.
- Wait about a day after the licences are assigned, without turning warm-up back on or sending a campaign: every refusal makes the reputation worse.
- Run a single test. If the error comes back, open a request with Microsoft support from the admin center, quoting error 550 5.7.708, to get an exception.
Your mailbox no longer receives its mail
Messages: None of the warmup emails sent to your address could be found in your mailbox… or Many of emails we send to your address has been rejected… Emails sent to your mailbox no longer arrive. Common causes: MX records changed during a migration, two competing sets of MX records (Google and Microsoft on the same domain), a full mailbox, a filter, or an Emelia connection still pointing at the old mailbox after a change of host.
If warm-up emails no longer arrive, neither do your prospects' replies. Fix the MX records at your host, reconnect the mailbox with its current settings, then turn warm-up back on.
The host suspended or blocked the mailbox
Messages: Your email host rejected the email with … outgoing mail is suspended… or Your own email server refused to send our warmup emails… Your host has blocked outgoing mail for the domain or the account: suspected spam, abuse, unpaid bill. Only the host can lift it. Contact its support, check that you can send again from your usual email client, then turn warm-up back on. Meanwhile, pause the campaigns sending from that mailbox.
A forward to an address that no longer exists
Message: Your mailbox forwards incoming emails to… Your mailbox forwards its mail to a dead address, and every warm-up email it receives triggers an error for the sender. Remove or fix the forwarding rule at your host, then turn warm-up back on. More broadly, avoid forwards and aliases on a mailbox in warm-up: they skew the stats.
The domain's DNS is incomplete
Message: We are not able to properly send email from this provider. Please check the configuration., followed by the details (sending refused, SPF, DMARC or MX missing). The test email could not be sent, or the domain has no MX record. Fix your records at your host (SPF, DKIM and DMARC), wait one to two hours, then turn warm-up back on.
Your subscription stopped
End of the free trial, failed payment, cancellation, or a switch to a plan with fewer mailboxes: warm-up stops with the subscription. A mailbox beyond your plan's quota shows the Expired badge (“This mailbox is disabled: your subscription no longer covers enough sending mailboxes.”). Settle the payment, or delete the extra mailboxes, then turn warm-up back on.
A bank direct debit sometimes arrives too late for the renewal date, and the account is cut off at every renewal. If warm-up stops every month on the same date, that is probably why: switch to a card.
What does not stop warm-up
- Weekends: the volume drops on purpose on Saturday and Sunday.
- The first days: only a few exchanges, and no score before four days of activity.
- A host's hourly limit: when your host caps sending per hour (OVH, for example, at 200 messages per hour per account), Emelia tries again later. Warm-up slows down but does not stop for that. Your campaigns, on the other hand, may see sends refused: spread your mailboxes over several domains or accounts.
- A page not reloaded: after turning warm-up on, reload the page before concluding that nothing works.
Turn warm-up back on
- Read the red reason and fix the cause. Turning it back on without fixing anything does not last: warm-up will stop again.
- If you touched the DNS, wait one to two hours, then click Re-check settings at the bottom of the detailed window.
- Switch it back on in the Warmup column, or tick several mailboxes and click Enable warmup.
- Wait a few seconds and reload the page: the flame should stay lit.
After a stop, warm-up resumes at the first step. The reputation the mailbox has already earned is not lost.
When to contact us
Write to us from Help & Support, in the left-hand menu, in these cases:
- Warm-up refuses to come back on with the message Warmup cannot be reactivated because it's not compatible with our system: you have already turned it back on three times after automatic stops, the next step goes through us.
- A Google Workspace or Microsoft 365 mailbox gets an incompatibility message: that is not normal.
- Warm-up stopped with no readable reason, or a healthy mailbox has not sent or received anything for several days.
- The score stays low while your campaigns have good open rates.
The mailbox address, its host, the red message copied as is, and the date of the last activity shown in the history.
Frequently asked questions
The questions we get asked on this topic, answered briefly.
Why did I not get any alert?
Emelia does not email you when warm-up stops. Get into the habit of glancing at the Warmup column on the Accounts page, say once a week: a snowflake with a clock next to it means a stop.
Should I delete and reconnect the mailbox?
Only if the cause is a disconnection or a change of host. Otherwise it is pointless: fix the cause and turn warm-up back on.
My warm-up stops again right after I turn it back on, why?
The cause has not been fixed, or it cannot be: that is typical of a host that blocks automated sending. Reread the red reason. If your sending server keeps refusing the emails, plan on Google Workspace or Microsoft 365 mailboxes.
My mailboxes are with OVH, is that compatible?
Generally yes. Keep in mind OVH's limit of 200 messages per hour per account, which slows warm-up down if many mailboxes share one account, and keep an eye on mailboxes on the Zimbra offer, which can disconnect: reconnect them as soon as they drop.
Can I keep running campaigns without warm-up?
Yes, nothing else depends on warm-up. On an already warmed-up mailbox with warm-up off, stay at 35 new contacts and 100 emails a day at most.