Does the X-Mailer header impact email deliverability in Zoho Campaigns?
Michael Ko
Co-founder & CEO, Suped
Published 10 Aug 2025
Updated 17 Aug 2025
8 min read
When you send emails through an email marketing platform like Zoho Campaigns, you might notice a small phrase appearing next to your sender name in recipients' inboxes, especially in services like Gmail. This often reads something like "Using Zoho Campaigns". This observation naturally leads to a question: does this additional information, specifically the X-Mailer header that drives it, impact your email deliverability?
Email deliverability is a complex topic influenced by many factors, from sender reputation to content quality and adherence to email authentication protocols. It is important to understand which elements truly matter and which are largely informational. In this discussion, we will explore the role of the X-Mailer header within the context of Zoho Campaigns and its implications for your messages reaching the inbox.
Understanding email headers and X-Mailer
Email headers are like the metadata of an email, containing crucial information about its journey from sender to recipient. They include details about the sender, recipient, subject, date, and various technical parameters that help mail servers process and route messages. You can learn more about how message headers reveal important details directly from Zoho's own documentation on message headers.
The X-Mailer header is a non-standard (or "X-") header that email clients or sending software can add to an email. Its primary purpose is to identify the program used to compose or transmit the email. For instance, if you send an email from Gmail.com directly, it might include an X-Mailer header indicating its origin. This header allows recipients to see what program the email originated from, as discussed in detail by Mutant Mail's blog on the X-Mailer field.
In the case of Zoho Campaigns, the platform automatically inserts an X-Mailer: Zoho Campaigns header into the emails you send. This is why recipients using email clients like Gmail might see "Using Zoho Campaigns" displayed next to your sender name, even if your From domain, return path, and DKIM domain are all properly configured to your own domain.
Does X-Mailer impact deliverability?
The short answer is no, the X-Mailer header typically does not directly impact email deliverability or inbox placement in Zoho Campaigns, or for any other sending platform. Modern spam filters and mailbox providers, including Zoho, focus on a much more sophisticated set of signals to determine whether an email should reach the inbox or be routed to the spam folder. These signals primarily revolve around sender reputation and robust email authentication.
Spam filters are far more concerned with factors such as your domain's reputation, engagement metrics (opens, clicks, unsubscribes, complaints), and the proper configuration of authentication protocols like SPF, DKIM, and DMARC. These protocols verify that an email is legitimate and truly comes from the stated sender, making them critical for successful email delivery. For a comprehensive guide on these, refer to a simple guide to DMARC, SPF, and DKIM.
The presence of an X-Mailer header, whether it specifies "Zoho Campaigns" or any other sending software, is generally a benign piece of information. It does not carry significant weight in the algorithms used by inbox providers to decide if an email is spam or not. In fact, many legitimate email clients and marketing platforms include this header by default.
Focus on core deliverability factors
Sender reputation: Maintain a healthy sender reputation by avoiding spam complaints and bounces.
Authentication protocols: Ensure your SPF, DKIM, and DMARC records are correctly set up. You can use a free DMARC record generator tool.
List hygiene: Regularly clean your mailing lists to remove inactive or invalid email addresses. This helps avoid spam traps and reduce bounce rates.
Content quality: Create valuable, relevant, and engaging content that recipients want to open and read.
Ultimately, your focus should be on establishing and maintaining a strong sender reputation and ensuring all your email authentication mechanisms are properly in place. If your emails are landing in spam, the X-Mailer header is highly unlikely to be the cause. Instead, investigate issues such as your DMARC reports, check for any blocklist (or blacklist) listings, or review your sending practices. For further insights into common deliverability problems, you can review why your emails are going to spam.
When X-Mailer could be a factor
While the X-Mailer header rarely, if ever, impacts deliverability directly, there are some minor considerations and edge cases worth noting. One theoretical scenario is if a specific X-Mailer string were to become heavily associated with spam or malicious activity across a wide range of mailbox providers. In such an extreme and unlikely case, filters might flag emails containing that specific header. However, for established platforms like Zoho Campaigns, this is extremely improbable as they actively work to maintain a clean sending reputation.
Another point is perception. Although the X-Mailer header doesn't affect automated spam filtering, the visible "Using Zoho Campaigns" text in the recipient's inbox might slightly alter how some recipients perceive your email. While most users likely won't pay attention, a small segment might notice it indicates a third-party sending service. This is more of a branding or transparency consideration than a deliverability concern.
Poor sender reputation: High bounce rates, spam complaints, or sending to invalid addresses.
Lack of authentication: Missing or misconfigured SPF, DKIM, or DMARC records can lead to emails being rejected or sent to spam. This is a common reason for deliverability issues.
Content issues: Spammy keywords, broken HTML, or suspicious links in the email body.
Blocklist listing: Your IP or domain being listed on a major email blacklist or blocklist (check with a blocklist checker).
X-Mailer header impact
Informational: Primarily indicates the sending software. Not typically used for spam scoring.
No direct filtering impact: Generally does not cause emails to go to spam or be rejected.
Rare edge cases: Only if a specific X-Mailer string is widely abused by spammers, which is highly unlikely for legitimate platforms like Zoho Campaigns.
Branding aspect: Can show recipients what software was used, a minor transparency point.
Managing X-Mailer in Zoho Campaigns
Many email service providers (ESPs), including Zoho Campaigns, add the X-Mailer header by default. As a user of Zoho Campaigns, you typically do not have direct control over whether this header is included or what value it contains. Most platforms do not offer an option to remove or customize this particular header because it serves an internal purpose for their own tracking and diagnostics, and as we've established, it doesn't generally affect deliverability. This means that even if you wanted to remove the "Using Zoho Campaigns" text, it's likely not an option available within the platform's settings. This is a common aspect of how your email tool affects your deliverability.
Example X-Mailer headertext
X-Mailer: Zoho Campaigns
Given that the X-Mailer header doesn't pose a direct threat to your email deliverability, the best approach is to concentrate your efforts on factors that genuinely influence whether your emails reach the inbox. This includes consistent list management, compelling content, and adherence to email authentication standards. These are the areas where you have significant control and where improvements will yield the most impactful results for your email marketing campaigns.
Final thoughts
The X-Mailer header, which often leads to the "Using Zoho Campaigns" display in recipient inboxes, is largely an informational component of your email. It identifies the sending software but does not, in itself, directly affect whether your emails land in the inbox or spam folder. Modern email deliverability is far more complex and relies on factors such as sender reputation, email authentication (SPF, DKIM, DMARC), and content quality.
While you typically cannot remove or customize the X-Mailer header when using Zoho Campaigns, this should not be a primary concern for your deliverability efforts. Instead, channel your focus into maintaining a robust sender reputation, ensuring proper email authentication, and crafting engaging content. By prioritizing these core aspects, you will maximize your email deliverability and achieve better results for your campaigns.
Views from the trenches
Best practices
Always prioritize setting up and verifying SPF, DKIM, and DMARC for your domain. These are the true foundations of deliverability, not the X-Mailer header.
Monitor your sender reputation metrics, such as complaint rates and bounce rates, within Zoho Campaigns and other tools to proactively address any issues.
Regularly segment your audience and personalize content to improve engagement, which signals to mailbox providers that your emails are valued by recipients.
Common pitfalls
Over-analyzing the impact of non-critical headers like X-Mailer, diverting attention from more impactful deliverability factors.
Neglecting to clean your email lists, leading to higher bounce rates and potential encounters with spam traps, which significantly harm sender reputation.
Failing to review and act on DMARC reports, which provide crucial insights into authentication failures and potential spoofing attempts.
Expert tips
If you observe unexpected 'via' or 'on behalf of' labels alongside 'Using Zoho Campaigns', double-check your DKIM alignment; this is often a separate authentication issue.
While X-Mailer doesn't affect filtering, some brands might prefer a fully branded experience. Consider whether Zoho Campaigns' display aligns with your overall brand transparency goals.
Focus on the 'why' behind any perceived deliverability drop. The X-Mailer header is almost never the direct cause. Look at hard bounces, spam reports, and authentication failures first.
Expert view
Expert from Email Geeks says they seriously doubt the X-Mailer header causes deliverability problems.
2024-02-07 - Email Geeks
Marketer view
Marketer from Email Geeks says the X-Mailer header identifies the program used to send the email and is often added by default by email service providers.
Gmail.com directly, it might include an X-Mailer header indicating its origin. This header allows recipients to see what program the email originated from, as discussed in detail by Mutant Mail's blog on the X-Mailer field.
Zoho Campaigns.
