Summary
Gmail flags outbound links due to a combination of factors relating to the linked website's reputation, content, and security, as well as the sender's email practices and authentication. These include the domain being on a Google Safe Browsing blacklist, having a low reputation (especially for new domains), containing low-quality or spammy content, a high rate of user-reported spam, malware or phishing activity, and issues with email authentication (SPF, DKIM, DMARC). Poor list hygiene (spam traps, unengaged subscribers), a bad IP reputation, link cloaking, or unusual strings in the URL can also contribute to the problem. Resolving this requires improving domain reputation, ensuring website security, cleaning email lists, setting up proper authentication, monitoring IP reputation, and avoiding deceptive linking practices.
Key findings
- Google Safe Browsing: Links to sites flagged by Google's Safe Browsing service will be blocked.
- Domain Reputation: Gmail considers the reputation of both the sending and linked-to domains.
- Content Quality: Low-quality, spammy, or suspicious content on the linked site triggers flags.
- Email Authentication: Missing or misconfigured SPF, DKIM, and DMARC records hurt sender reputation.
- List Hygiene: Sending to spam traps and unengaged subscribers damages sender reputation.
- IP Reputation: A negative IP address reputation affects link deliverability.
- Link Cloaking: Deceptive link cloaking techniques can trigger spam filters.
- High Spam Rate: High user-reported spam rates negatively impact the reputation of included links.
- Malware/Phishing: Detection of malware or phishing activity on the linked website will cause flagging.
Key considerations
- Check Safe Browsing Status: Verify that the linked domain is not listed on Google's Safe Browsing diagnostic page.
- Warm-Up New Domains: Gradually increase email volume from new domains to build reputation.
- Improve Content Quality: Ensure the linked website has valuable, trustworthy, and non-spammy content.
- Implement Email Authentication: Configure SPF, DKIM, and DMARC records for your sending domain.
- Maintain List Hygiene: Regularly remove inactive subscribers and validate email addresses to minimize spam traps.
- Monitor IP Reputation: Track your sending IP address reputation and take corrective actions if needed.
- Use Direct Links: Avoid link shorteners and cloaking techniques for transparency.
- Lower Spam Complaint Rate: Improve targeting and email content to reduce user-reported spam complaints.
- Ensure Website Security: Keep the linked website free from malware and phishing threats.
- Review Blog Comments: Check blog comments for any malicious or spam links which might cause your personal blog to be flagged.
What email marketers say
13 marketer opinions
Gmail flags outbound links due to various factors related to the link's destination, the sender's reputation, and email content/configuration. Issues range from the linked domain's reputation, presence on blacklists, or association with spam/malware, to problems with the sender's email authentication, IP reputation, or list hygiene. Resolving the issue involves addressing these potential problems through domain warming, content review, link validation, email authentication setup, and list cleaning.
Key opinions
- Web Risk Flagging: The linked website may be flagged by Google's Safe Browsing service due to reports of malicious activity.
- Domain Reputation: Gmail considers the reputation of the linked domain. New or domains with a history of spam are more likely to be flagged.
- Content Issues: The content of the linked website may trigger spam filters if it's low-quality, suspicious, or contains spammy keywords.
- Email Authentication: Lack of proper SPF, DKIM, and DMARC records can damage sender reputation and increase the likelihood of links being flagged.
- List Hygiene: Sending emails to spam traps or unengaged subscribers hurts sender reputation and can lead to link flagging.
- IP Reputation: A poor IP address reputation due to association with spam activity can cause Gmail to flag outbound links.
Key considerations
- Safe Browsing Report: Check if the domain is listed in Google's Safe Browsing report and address any identified issues.
- Domain Warming: For new domains, gradually increase email volume to establish a positive sending reputation.
- Content Review: Ensure the linked website's content is high-quality, trustworthy, and free of spammy elements.
- Email Authentication Setup: Implement SPF, DKIM, and DMARC records to authenticate your emails and improve deliverability.
- List Cleaning: Regularly clean your email list to remove inactive subscribers and spam traps.
- IP Reputation Monitoring: Monitor your IP address reputation and take action to improve it if it's low.
- Link Transparency: Avoid using link shorteners or cloaking techniques, and ensure that links are valid and direct.
Marketer view
Marketer from Email Geeks suggests that if the blog allows comments, a spam or phishing link in the comments could be causing the issue.
20 Nov 2023 - Email Geeks
Marketer view
Email marketer from Stack Overflow explains that Gmail might flag links if the domain lacks a strong reputation. Establishing domain authority through consistent, positive engagement and ensuring the domain isn't associated with spam can help.
22 Dec 2023 - Stack Overflow
What the experts say
2 expert opinions
Gmail may flag outbound links due to the linked domain's reputation, particularly if it's new or associated with low-quality content. Additionally, techniques like link cloaking, where the displayed URL differs from the destination, can trigger flagging. Resolving this involves building a positive domain reputation through consistent sending practices and ensuring transparent, direct linking.
Key opinions
- Domain Reputation: New or low-quality domains are more likely to have links flagged by Gmail.
- Link Cloaking: Using link cloaking techniques can lead to links being flagged.
Key considerations
- Reputation Building: Focus on building a positive sending reputation through consistent, high-quality content.
- Transparent Linking: Use clear, direct links that accurately reflect the destination URL.
Expert view
Expert from Word to the Wise explains that Gmail may be flagging links due to the domain's reputation, especially if the domain is new or has a history of sending low-quality content. Building a good sending reputation takes time and consistency.
1 Nov 2024 - Word to the Wise
Expert view
Expert from Spam Resource responds that Gmail may flag links if it detects techniques such as link cloaking (where the displayed URL is different from the actual destination). Ensure transparency by using clear and direct links.
26 Dec 2023 - Spam Resource
What the documentation says
3 technical articles
Gmail flags outbound links due to a high spam rate reported by users, the detection of malware or phishing on the linked website, or incorrect DNS records (SPF, DKIM, DMARC). These factors negatively impact sender reputation and user safety.
Key findings
- High Spam Rate: User-reported spam complaints significantly damage link reputation.
- Malware/Phishing: Detection of malicious activity on the linked website leads to immediate flagging.
- Incorrect DNS Records: Improperly configured or missing SPF, DKIM, and DMARC records compromise sender authentication.
Key considerations
- Reduce Spam Rate: Monitor and reduce spam complaints by improving email content and targeting.
- Website Security: Ensure the linked website is free from malware and phishing threats.
- DNS Configuration: Correctly configure SPF, DKIM, and DMARC records to authenticate email and improve sender reputation.
Technical article
Documentation from Google Search Central indicates that if Google detects malware or phishing activity on the linked website, Gmail will flag the links to protect users, regardless of the sender's reputation.
31 Mar 2025 - Google
Technical article
Documentation from Google Postmaster Tools explains that a high spam rate reported by users for emails from a domain can negatively impact the reputation of links included in those emails, leading to flagging.
7 May 2022 - Google
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