---
title: "How to Fix sailthru.com Spam Issues with Proper SPF Setup | AutoSPF"
description: "Fix sailthru.com spam issues by configuring SPF correctly. Learn how to authenticate your domain, improve email deliverability, and keep messages out of spam."
image: "https://autospf.com/og/blog/how-to-fix-sailthru-com-spam-issues-with-proper-spf-setup.png"
canonical: "https://autospf.com/blog/how-to-fix-sailthru-com-spam-issues-with-proper-spf-setup/"
---

Quick Answer

Learn how to fix sailthru.com spam issues by configuring your SPF record correctly. This guide explains how SPF authenticates outbound emails, prevents spoofing, improves inbox placement, and reduces the chances of your Sailthru emails being marked as spam.

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![Fix sailthru.com](https://media.mailhop.org/autospf/spf-record-office-365-6034-1785405104274.jpg) 

When **Sailthru emails** consistently land in recipients’ [spam folders](https://cybernews.com/news/microsofts-breach-notification-emails-end-up-in-spam-folder/), the cause is often an email authentication issue rather than the email platform itself. Mailbox providers such as Gmail, Outlook, Yahoo, and Apple Mail verify SPF, DKIM, and DMARC records before deciding whether to deliver messages to the inbox. An incomplete or misconfigured SPF record can reduce sender trust and negatively affect email deliverability.

Sailthru is an [email service provider](https://www.activecampaign.com/glossary/email-service-provider) used by publishers, retailers, media brands, and other Businesses for email marketing, newsletters, transactional notices, promotions, and informational notification campaigns. Because Sailthru sends high volumes of [bulk email](https://www.campaignmonitor.com/resources/glossary/bulk-email/), mailbox providers look closely at whether the sending domain is authorized. If SPF, DKIM, or DMARC are missing or misaligned, even legitimate messages from sailthru.com can resemble spam mail, junk email, or scam mail.

Proper email authentication is one of the most important factors influencing inbox placement. Correctly configured SPF, together with DKIM and DMARC, helps mailbox providers verify your sending domain and improves **trust in your email messages**.

### Why legitimate mail can look like abuse

Legitimate Sailthru campaigns can sometimes be mistaken for phishing or spam if the subject line is misleading, the **sender’s branding** is inconsistent, or the “From” address differs from the website where the recipient originally subscribed. When recipients do not recognize the sender, they are more likely to ignore the message, mark it as spam, or unsubscribe. _Properly configuring SPF, along with DKIM and DMARC, helps mailbox providers verify that your emails are authentic and improves recipient trust_.

That is why proper SPF setup matters: it gives mailbox providers technical evidence that your domain authorizes Sailthru to send for your brand. [AutoSPF](https://autospf.com/) makes it easier to manage complex SPF records for multiple email services.

## How SPF Authentication Works for Sailthru Email Sending

SPF, or Sender Policy Framework, is a DNS-based authentication method that tells receiving [mail servers](https://www.techtarget.com/whatis/definition/mail-server-mail-transfer-transport-agent-MTA-mail-router-Internet-mailer) which systems are allowed to send mail for a domain. For Sailthru sending, SPF helps confirm that mail using your **envelope sender**, bounce domain, or return-path domain is authorized by your [DNS records](https://www.ibm.com/think/topics/dns-records).

When Gmail receives a message connected to sailthru.com, it checks DNS records for the domain used in the [return path](https://www.zoho.com/zeptomail/glossary/return-path.html). If the SPF record includes the appropriate Sailthru sending infrastructure, Gmail can pass SPF. If the required **SPF authorization** is missing or incorrect, SPF authentication may fail. This can reduce sender trust and increase the likelihood that messages are filtered to spam or rejected by receiving mail servers.

Your [SPF record](https://autospf.com/blog/what-spf-records-are-and-how-they-protect-email-domains/) should include the mechanism provided in Sailthru’s official documentation or account settings. Always verify the correct value before updating your DNS records.

_However, the correct include depends on your Sailthru configuration, your branded sending domain, and current Sailthru documentation_. Always verify the exact value with Sailthru support, your account documentation, or the Sailthru abuse team if you are investigating spam or suspicious traffic.

![Multiple Spf Records 3000](https://media.mailhop.org/autospf/multiple-spf-records-3000-1785405149157.jpg)

### SPF, DKIM, and DMARC alignment

SPF alone is not a complete **deliverability strategy**. Gmail and Google increasingly expect authenticated mail to use SPF, DKIM, and DMARC together. SPF authorizes the sending infrastructure. DKIM signs the message. [DMARC checks](https://autospf.com/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dmarc-record-check/) alignment and tells receivers what to do if authentication fails.

### Understanding Sailthru in the Email Authentication Process

A recipient may see sailthru.com in headers, tracking links, or return-path details even when the visible From name is a brand. This is normal for many Email Service Providers, but it can confuse recipients who search from:_sailthru_.com in Gmail and decide the message is spam mail. If users cannot identify the sender, they may click unsubscribe, ask to remove from list, or mark the campaign as [email spam](https://www.darkreading.com/physical-security/spam-emails-bring-bomb-threats-to-us-businesses-schools).

To reduce confusion, ensure the visible sender name, reply-to contact email, footer address, and Privacy Policy are consistent with your brand. If someone is already unsubscribed, your systems should honor that status and remove from **future send workflows**.

## Common SPF Misconfigurations That Cause sailthru.com Spam Issues

_The most common SPF issue is a missing or incorrect Sailthru include in your SPF record_. If your domain sends email through Sailthru but your DNS does not authorize its sending infrastructure, SPF authentication may fail. As a result, mailbox providers such as **Gmail, Outlook, and Yahoo** may classify your [messages as suspicious](https://www.cybersecuritydive.com/news/fbi-us-officials-impersonated-text-ai-voice/748334/), reducing inbox placement and increasing the likelihood that emails are filtered to the spam folder. Regularly reviewing and validating your SPF record helps ensure your Sailthru emails are properly authenticated and delivered successfully.

Another frequent issue is having more than one [SPF TXT record](https://autospf.com/blog/what-is-a-txt-spf-record-and-why-is-it-important/) for the same domain. SPF requires a single TXT record **beginning with `v=spf1`**. Multiple SPF records can cause permanent errors, leading to authentication failure and more email spam treatment.

![Kitterman Spf 8888](https://media.mailhop.org/autospf/kitterman-spf-8888-1785405191942.jpg)

### SPF mistakes to check first

Common misconfigurations include:

- Multiple SPF records on the same sending domain
- Missing or outdated Sailthru include mechanism
- Too many DNS lookups, exceeding the SPF 10-lookup limit
- Incorrect use of -all, \~all, or ?all
- Authorizing the [root domain](https://www.siteground.com/kb/what-is-a-root-domain) but not the branded bounce domain
- Sending from a domain different from the authenticated domain
- Not updating SPF after adding new Advertising Partners or platforms
- Using from:_sailthru_.com filtering assumptions instead of reviewing full headers

![Spf Record Checker 1020](https://media.mailhop.org/autospf/spf-record-checker-1020-1785405298940.jpg)

### Authentication Issues Can Affect Sender Reputation

SPF misconfigurations can negatively impact your **domain’s sending reputation** over time. When mailbox providers repeatedly detect authentication failures, they may become less likely to trust future messages from your domain, reducing inbox placement and increasing the likelihood that emails are filtered as spam.

Maintaining accurate SPF records, together with properly configured DKIM and DMARC, helps establish sender trust and supports consistent email deliverability. Regularly reviewing your DNS records, validating authentication settings, and updating your SPF record when adding new email services can help prevent authentication failures and improve the reliability of your **Sailthru email campaigns**.

![Brad Slavin](https://media.mailhop.org/autospf/images/authors/brad-slavin.jpg) 

[ Brad Slavin ](/authors/brad-slavin/) 

General Manager

Founder and General Manager of DuoCircle. Product strategy and commercial lead for AutoSPF's 2,000+ customer base.

[LinkedIn Profile →](https://www.linkedin.com/in/bradslavin) 

## Ready to get started?

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[ Book a Demo ](/book-a-demo/) 

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