Summary
The overwhelming consensus among email marketing experts and deliverability documentation is that words like 'Viagra' are extremely potent spam triggers. These terms are deeply ingrained in the algorithms of major spam filters, including those used by providers like Gmail, Microsoft Exchange Online Protection, and Mailchimp. Historically associated with unsolicited and often illicit content, their presence in subject lines, and even body copy, almost guarantees that an email will be flagged, quarantined, or sent directly to the spam folder, regardless of the message's legitimacy. While some large providers may possess sophisticated filters capable of nuanced content analysis, the prevailing view is that using such high-risk keywords will severely impair deliverability, leading to poor sender reputation and limited inbox placement.
Key findings
- Universal Spam Trigger: Words like 'Viagra' are widely recognized and highly weighted by nearly all spam filters, including major Email Service Providers, due to their historical association with illicit and unsolicited commercial emails.
- Immediate Filtering Risk: The inclusion of such terms, especially in subject lines, significantly increases an email's spam score, almost guaranteeing it will be blocked, sent to the junk folder, or quarantined, bypassing the inbox entirely.
- Context Irrelevant: Even when used in legitimate contexts, these words are so deeply hard-coded into filter logic that they are highly likely to trigger a spam designation, overriding other positive deliverability signals. This is a surefire way to trigger filters.
- Negative Sender Reputation Impact: Consistent use of such high-risk keywords can harm a sender's overall reputation, making it harder for future emails to reach the inbox, even those without problematic content.
Key considerations
- Avoid Keywords: For optimal deliverability, it is strongly advised to completely avoid using words like 'Viagra' in email subject lines and body content. Even if your email is legitimate, these terms are heavily weighted by spam filters.
- Recipient Perception: Beyond automated filters, using such words can also negatively influence recipient perception, increasing the likelihood of manual spam reports, which further harms sender reputation.
- Varying Filter Sophistication: While some advanced filters might attempt to distinguish context, many, especially those of smaller ISPs, will apply a blanket rule, making avoidance the safest strategy for broad reach. Even major providers, despite their sophistication, are highly likely to flag these terms.
- Emphasize Best Practices: Ensuring high deliverability is best achieved by adhering to general email marketing best practices, such as maintaining a clean list, sending relevant content, and authenticating emails, rather than attempting to navigate sensitive keywords. Spell sensitive words correctly and avoid alternative characters if using them, though it's best to avoid these terms altogether.
What email marketers say
12 marketer opinions
Words such as 'Viagra' are widely considered to be among the most potent and historically problematic spam triggers for email deliverability. Across the board, email marketers and deliverability specialists agree that these terms, especially in subject lines, are almost universally flagged by spam filters. This is largely due to their long history of abuse in unsolicited commercial emails. Their presence significantly elevates an email's spam score, leading to a high probability of being blocked, quarantined, or delivered directly to the junk folder, irrespective of the email's actual content or sender's legitimacy. While filter sophistication varies, the consensus is that using these keywords poses an undeniable risk to inbox placement and sender reputation.
Key opinions
- High Trigger Risk: Words like 'Viagra' are universally recognized as immediate and potent spam triggers by nearly all email filters, including those from major providers.
- Historical Precedent: Their inclusion is flagged due to decades of association with unsolicited and often illicit pharmaceutical spam, leading to these terms being hard-coded into filter algorithms.
- Context Does Not Override: The legitimate context of an email often fails to prevent filtering, as these words are such strong signals that they tend to override other positive deliverability factors.
- Deliverability Catastrophe: Using such terms severely impairs inbox placement, almost guaranteeing that emails will be blocked, quarantined, or routed directly to the spam folder, bypassing the inbox entirely.
Key considerations
- Strict Avoidance: For the highest deliverability rates, completely avoid using terms like 'Viagra' in email subject lines and body content. Even a legitimate context is unlikely to bypass the deeply ingrained filter rules for these words.
- Recipient Trust: Beyond automated filters, employing such terms can negatively impact how recipients perceive your brand, potentially leading to increased manual spam reports and a damaged sender reputation.
- Varying Filter Strength: While some large providers may have nuanced filters, many, especially smaller or less sophisticated ISPs, will apply a blanket rule to these words. This makes avoiding them the most reliable strategy for broad inbox reach.
- Focus on Reputation: Building and maintaining a strong sender reputation through a clean email list, relevant content, and proper email authentication is far more effective than attempting to use or navigate around historically problematic keywords.
Marketer view
Email marketer from Email Geeks explains that large provider filters can distinguish between legitimate studies mentioning 'viagra' and unsolicited offers.
13 Jun 2023 - Email Geeks
Marketer view
Email marketer from Email Geeks shares that while major providers handle sensitive words, smaller, less sophisticated ISPs might still flag such content, but professional accounts usually avoid these.
2 May 2025 - Email Geeks
What the experts say
3 expert opinions
Words like 'Viagra' continue to be significant spam triggers, particularly for content filters that actively scan messages for common spammy terms. While the sophistication of spam filters, including those on corporate networks, has advanced beyond some outdated concerns, the presence of these specific words still serves as a clear signal to classify an email as potential spam. Experts emphasize that employing correct spelling for any sensitive terms, rather than attempting to circumvent filters with alternative characters or spacing, is crucial if these words must be used. Ultimately, focusing on overall good email practices is paramount for ensuring strong deliverability.
Key opinions
- Content Filter Target: Content-based spam filters are specifically programmed to identify and flag common spam keywords, such as 'Viagra' and 'refinance,' within email subject lines and body copy.
- Clear Spam Signal: The inclusion of these high-risk words acts as a direct and strong signal to email filters, indicating a high likelihood that the message is unsolicited or spam.
- Evolving Filter Landscape: Despite advancements in filter sophistication, which may have reduced some outdated concerns, sensitive terms like 'Viagra' still pose a significant deliverability risk across various email networks.
Key considerations
- Accurate Spelling: If sensitive words absolutely must be used, always spell them correctly. Avoid using alternative characters, extra spaces, or phonetic spellings, as these attempts to bypass filters can often backfire and further harm deliverability.
- Holistic Deliverability: Prioritize comprehensive email deliverability strategies, including list hygiene, engaging content, and proper authentication, rather than solely focusing on individual word choices to ensure inbox placement.
- Modern Filter Logic: While corporate network filters have become more advanced, the inherent risk associated with historically spammy terms persists. Do not assume modern filters will always correctly discern legitimate context for such words.
Expert view
Expert from Email Geeks advises to spell sensitive words correctly and avoid alternative characters or spacing, emphasizing that good email practices help ensure deliverability.
9 Aug 2024 - Email Geeks
Expert view
Expert from Email Geeks indicates that outdated concerns about sensitive words on corporate networks are likely no longer valid due to improved filter sophistication.
20 Jul 2021 - Email Geeks
What the documentation says
6 technical articles
Spam filters, supported by documentation from major email service providers and deliverability experts, consistently flag words such as 'Viagra' as high-risk terms. These words are deeply embedded in content analysis algorithms and specific rules designed to identify unsolicited commercial emails. Their presence in subject lines or email bodies significantly increases an email's spam score, leading to a very high probability of the message being quarantined, junked, or outright blocked, regardless of the sender's intent. This consensus underscores that despite evolving filter technologies, these historically problematic terms remain a serious impediment to successful inbox placement.
Key findings
- Algorithmic Flagging: Spam filters, including those from major providers like SpamAssassin, Microsoft EOP, and Gmail, use specific rules and content analysis to heavily weight and flag terms like 'Viagra'.
- Increased Spam Score: The presence of such words dramatically elevates an email's internal spam score, making it highly susceptible to filtering actions.
- High Filtering Probability: Emails containing these terms face an extremely high likelihood of being quarantined, diverted to the junk folder, or completely blocked by recipient servers.
- Universal Consensus: Deliverability experts and major Email Service Providers universally advise against using these words due to their well-documented history of triggering filters and impairing deliverability.
Key considerations
- Absolute Avoidance: To ensure optimal inbox placement, senders should completely avoid using terms like 'Viagra' in email subject lines and body content, as they are direct spam triggers.
- Rule-Based Filtering: Be aware that filters use specific, weighted rules targeting these types of pharmaceutical terms, making it difficult to bypass detection, even with otherwise legitimate content.
- Broad Impact: Their use not only triggers automated filters but can also negatively influence recipient trust and significantly harm overall sender reputation over time.
- Prioritize Deliverability Fundamentals: Instead of attempting to navigate or disguise high-risk words, focus on maintaining a clean email list, authenticating emails, and providing valuable, relevant content to build a strong sender reputation.
Technical article
Documentation from SpamAssassin Wiki explains that words commonly associated with spam, such as 'Viagra' and similar pharmaceutical terms, are highly weighted by spam filters like SpamAssassin. These words trigger specific rules designed to identify unsolicited commercial email, leading to a significant increase in the spam score and a high likelihood of the email being filtered.
26 Jan 2025 - SpamAssassin Wiki
Technical article
Documentation from Mailchimp Knowledge Base shares that content commonly associated with spam, including adult products, pharmaceuticals, and 'get rich quick' schemes, is heavily scrutinized by spam filters. While not listing specific words, they advise against anything that resembles these categories, implying that words like 'Viagra' would trigger their internal compliance and external spam filters.
5 Aug 2023 - Mailchimp Knowledge Base
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