When will Zoho Campaigns suspend a campaign
In short: Zoho Campaigns suspends a campaign when its anti-spam system spots signals of spam or poor sending practices — a blocklisted sender domain or IP, problematic links (blocklisted, shortened, broken, or direct-download URLs), spammy or restricted content, a suspicious or low-quality mailing list, spam-trap hits, or spam complaints, bounces, and unsubscribes that cross the thresholds in our terms of use. The fix is the same discipline that prevents it: authenticate with SPF, DKIM, and DMARC, suppress bounces, honor one-click unsubscribe, and mail a clean, permission-based list.
At Zoho Campaigns, we are committed to offering a safe email experience for our users, which is why we built an efficient email infrastructure that wards off malicious emails with ease. We thoroughly scrutinize all the campaigns sent by users to identify patterns that point to spam. Our anti-spam system will validate all campaigns and the sending practices associated with them. If our anti-spam system finds anomalies in a campaign's content and sending practices, we will suspend the campaign. Let's dive deep and learn more about the reasons your campaign may get suspended:
Blacklisted sender domain and IP address
At Zoho Campaigns, if a user uses a blacklisted sender domain or a blacklisted IP address to send campaigns, we will suspend the campaign. We urge our users to ensure that the sender domain and the IP address earns a positive reputation and stays in the good books of mailbox providers and anti-spam services. We also recommend users check the blacklists once in a while and ensure that their sender domain and the IP address is not listed in them.
A critical part of maintaining a trustworthy sender domain is proper email authentication. Since February 2024, Google and Yahoo require all bulk senders to authenticate their email with SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail), and to publish a DMARC record for their sending domain. Microsoft extended the same requirement to Outlook, Hotmail, and Live.com addresses in May 2025. A DMARC policy of p=none is the minimum required for compliance, but we strongly recommend progressing to p=quarantine or p=reject to provide meaningful protection against domain spoofing and phishing. We also encourage you to monitor your sending domain's reputation using Google Postmaster Tools, which gives you authoritative, real-time insight into how Gmail views your domain.
Issues with the email content
Blacklisted URLs
Major mailbox service providers and anti-spam services are hugely concerned about the URLs used in emails and may deny inbox placement if the URLs are found to be blacklisted. At Zoho Campaigns, if our users use blacklisted URLs in their campaigns, we will temporarily suspend campaign sending for those users.
Shortened URLs and URLs with multiple redirects
Mailbox providers consider shortened URLs and URLs with multiple redirects to be suspicious. While scanning incoming emails, if the receiving servers of mailbox providers find shortened URLs and URLs with multiple redirects, they may either flag your email as spam or quarantine the email. To prevent this, we will suspend the campaigns that contain shortened, broken, invalid URLs, and URLs with multiple redirects.
Broken URLs
Broken URLs are those that don't work. When email recipients click a broken URL, they will see a 404 Error page. When the receiving servers of mailbox providers find broken URLs in the email message, they mark the email as spam.
Direct download link
A direct download link is a URL that can be used to download files directly rather than visiting a website and downloading it from there. Spammers often use direct download links to spread malicious software. So, our anti-spam system will suspend campaigns that contain direct download links.
Inappropriate or suspicious content
Our anti-spam engine scrutinizes all the campaigns sent by our users. While scanning the campaign, we look for spam trigger words, pornographic content, and content related to restricted businesses mentioned in our terms of use. If a campaign contains such content, we will suspend the campaign and block the user's account.
Issues with the mailing list
When the source of the mailing list is suspicious
At Zoho Campaigns, we will assess all the attributes of an email campaign before approving it. This includes the mailing lists as well. While reviewing a campaign, if we consider the source of the mailing list to be suspicious, we will suspend the campaign and ask the user to offer detailed information about the source of the signups.
Poor mailing list quality
If a lot of the recipients negatively engage with a campaign sent by a user, it may be due to the quality of the mailing list. In such situations, we will temporarily suspend campaign sending and verify the quality of the mailing list. We will request the user to prune the mailing lists. If the user hasn't brought back inactive contacts to the active state and removed disengaged contacts, we will not allow the user to send campaigns. We do this to prevent further damage to our sender domain and IP address. We'll only approve campaigns if the user cleans the mailing list and adopts hygienic email sending practices.
Spam trap hits
A spam trap is an email address used by mailbox providers and anti-spam organizations to identify senders with poor acquisition or list hygiene practices. It is not associated with any real user and is never intended to receive legitimate email. There are two main categories of spam trap that senders are likely to encounter. Pristine spam traps are addresses that have never belonged to a real person and were created solely to catch senders who harvest, scrape, or purchase email lists. Recycled spam traps are addresses that once belonged to real users but were abandoned, deactivated, and later repurposed by mailbox providers to flag senders who fail to remove inactive contacts from their lists. Typo spam traps are addresses at commonly misspelled domains that catch senders who do not validate email input at the point of collection.
If your campaign hits spam traps, it will incur a negative reputation for the sender domain and the IP address. At Zoho Campaigns, we take spam trap hits seriously. If campaigns sent by any of our users hit spam traps, we will temporarily suspend email sending for the user.
Spam and abuse complaints
At Zoho Campaigns, we address spam and abuse complaints with the utmost care and work to resolve them as soon as possible. Whenever your contacts mark your emails as spam, it will affect not only your business but also our sender domain, IP address, and other users using the system. It also damages our reputation with mailbox service providers and anti-spam services.
We have mentioned the threshold value for spam complaint rates in our terms of use. When the spam rate of a campaign sent by a user exceeds the threshold value, we will stop sending the campaign. As a widely recognized industry benchmark, Google's bulk sender guidelines — in effect since February 2024 — specify that senders should maintain a spam complaint rate below 0.10% as a routine target, and must never allow the rate to reach 0.30% or above. These rates can be tracked directly through Google Postmaster Tools. We strongly recommend monitoring your spam complaint rate through this tool so that you can take corrective action well before reaching the threshold.
High bounce rate
Bounces occur when sent email can't be delivered. A high bounce rate will incur a negative reputation for the sender domain and IP address. This will affect deliverability for other users using our sender domain and IP address. Also, a high bounce rate will push us into the bad books of the mailbox service providers and anti-spam services. At Zoho Campaigns, we have defined the threshold values for hard bounces and mentioned it in our terms of use. When the hard bounce rate of a campaign sent by our users exceeds the threshold value, we will temporarily suspend campaign sending for the user.
To protect your sender reputation, we recommend suppressing hard-bounced addresses immediately after they are returned. For soft bounces — which are temporary delivery failures — it is best practice to suppress an address after three to five consecutive soft bounce events, as repeated attempts to reach an unreachable mailbox generate the same negative reputation signals as sending to invalid addresses.
High unsubscribes
Mailbox service providers closely monitor email engagement to make inbox decisions. If your campaign receives a lot of unsubscribes, it will incur a negative reputation for the sender domain and IP address. This will severely affect inbox placement for other users using the IP address. At Zoho Campaigns, we have mentioned in our terms of use that the unsubscribes count should not be greater than the click rate. If a campaign sent by a user receives a lot of unsubscribes, we will temporarily suspend campaign sending for the user.
Making it easy for recipients to unsubscribe is also now a requirement of the major mailbox providers. Since February 2024, Google and Yahoo have required bulk senders — those sending 5,000 or more messages per day — to implement one-click unsubscribe via the List-Unsubscribe and List-Unsubscribe-Post headers as defined in RFC 8058. Microsoft extended the same requirement to its consumer email services in May 2025. Under this standard, unsubscribe requests surfaced by the mailbox provider's interface must be honored and processed within 48 hours. Zoho Campaigns automatically includes the required headers in your marketing campaigns, but if you use custom sending infrastructure, you should verify that your setup is RFC 8058 compliant. Providing a frictionless unsubscribe experience benefits your reputation as well: recipients who can easily opt out are far less likely to mark your email as spam instead.
At Zoho Campaigns, we strive hard to offer a safe email experience for our users, which is why we have built a super-efficient anti-spam engine that helps us effortlessly identify and thwart spam. We also urge businesses to adopt hygienic email sending practices so that they can improve email deliverability and maximize their conversions.