Why do emails sent via Gmail sometimes bypass blocks that SalesLoft or Salesforce encounter?
Michael Ko
Co-founder & CEO, Suped
Published 20 Jul 2025
Updated 15 Aug 2025
7 min read
Many sales teams using platforms like SalesLoft or Salesforce have observed a curious phenomenon. When their outbound emails get blocked or bounce, they sometimes find that resending the same message directly from their Gmail accounts leads to successful delivery. This often leads them to believe they've bypassed a firewall or a blocklist (or blacklist) restriction.
It can be confusing, especially since these sales engagement tools frequently integrate with Google Workspace (Gmail) accounts, seemingly sending emails from your Gmail account anyway. The expectation is that sending directly from Gmail would yield the same result as sending through the platform, but this isn't always the case.
The core of the issue lies in how automated sales tools handle email versus how Gmail handles a personal email sent manually. While both originate from a Gmail account, the underlying technical characteristics of the emails differ significantly. These differences are what mailbox providers (like Google and Microsoft) analyze to determine inbox placement, or if the email gets blocked altogether. This behavior often affects sales reps' Google Workspace emails.
The mechanics of sales engagement platforms
Sales engagement platforms like SalesLoft and Salesforce are designed to scale outreach efforts. To achieve this, they often modify emails in ways that might not be immediately obvious. These modifications, while functional for tracking and automation, can trigger spam filters and blocklists (or blacklists).
One of the primary culprits is the inclusion of tracking pixels and wrapped links. A tracking pixel is typically a tiny, transparent image (often 1x1 GIF) embedded in the email HTML. When the recipient opens the email, this pixel loads, notifying the sender that the email was opened. Similarly, links in the email might be rewritten or wrapped to go through the sales platform's tracking domain before redirecting to the actual destination. This allows for click tracking.
While these features are essential for sales analytics, they fundamentally alter the email's content and structure. They introduce external domains (even if hosted on your own domain, like a CNAME) and patterns that can be easily identified as characteristic of automated or mass emailing, rather than a personal, one-to-one communication. This is a common reason why Salesforce emails can encounter delivery problems.
Mailbox providers like Google have highly sophisticated spam filtering algorithms that go far beyond just checking authentication records (SPF, DKIM, DMARC). They analyze a vast array of signals, including sender reputation, content, formatting, and sending behavior. When an email contains tracking elements or wrapped links, these are often red flags.
Even if your domain's authentication is perfectly set up and your sender reputation is good, the presence of these automated indicators can tell the recipient's mail server that the email is part of a bulk campaign. This can lead to a phenomenon known as shadow-throttling or silent blocking, where emails are quietly shunted to spam or dropped without a bounce message, impacting email deliverability rates.
The sender reputation of Google's main sending infrastructure is extremely high, as millions of legitimate individual emails are sent through it every day. When you send directly from your Gmail interface, your email benefits from this inherent trust. Sales platforms, even when sending via your Gmail account, often introduce subtle changes that make the email look less like a human-sent email and more like an automated one.
Tracking elements: Often include hidden pixels and wrapped links for analytics.
Headers: May add additional headers that identify the sending software.
Sending volume: Designed for higher volumes, which can be flagged by ISPs.
Content variations: Templates and merge tags can sometimes look less natural.
Native Gmail sending
No tracking: Emails sent directly from Gmail typically do not have these elements.
Clean headers: Headers reflect standard Google mail routing, which is trusted.
Lower volume: Perceived as lower volume, one-to-one communication.
Organic content: Appears to be composed manually, which is favored by filters.
The impact on deliverability and trust
The impact of these automated indicators can be significant. When an email is identified as part of a mass sending campaign, even if it's sent from a legitimate domain, it faces a higher likelihood of being classified as spam or blocked outright. This is because mailbox providers are constantly trying to protect their users from unwanted emails, whether they are outright phishing attempts or aggressive sales outreach.
For instance, a recipient's mail server might use DNS-based blocklists (DNSBLs) that flag domains or IPs associated with high-volume or aggressive sending. If the sales platform's infrastructure (or even your own domain when configured by the platform) lands on such a blacklist, delivery will suffer. Even if not on a public blacklist, private blocklists maintained by ISPs can cause delivery issues.
Furthermore, the content itself can be scrutinized. If an email from a sales tool mimics spam characteristics, even inadvertently, it can be filtered. The psychological aspect is also at play: a manually sent email often feels more genuine and less intrusive to a recipient, leading to fewer complaints and better engagement. Mailbox providers interpret these positive user interactions as signs of legitimate mail.
Strategies for improving deliverability
While sending directly from Gmail might offer a short-term workaround for individual blocked emails, it's not a scalable or sustainable solution for sales teams. The key to long-term deliverability when using sales engagement platforms lies in optimizing their configuration and your sending practices. For businesses facing sudden rejections by Gmail, a comprehensive approach is necessary.
Focus on email authentication: ensure your SPF, DKIM, and DMARC records are correctly configured for your sending domain, especially for the domains your sales platforms are using. This verifies to mailbox providers that you are a legitimate sender. It can even impact how SPF hard fails are handled.
Beyond technical settings, consider the content and volume of your outreach. Personalize emails as much as possible, avoid spammy keywords, and segment your lists to ensure relevance. Gradually increasing your sending volume (warming up) can also help build a positive sender reputation. Monitoring your deliverability is also important. For example, Salesforce emails often face blocks, and understanding why is the first step to a solution.
Best practices for sales platforms
Use custom tracking domains: Configure your sales platform to use a subdomain of your primary domain for link wrapping and tracking pixels. This makes the emails appear more legitimate compared to using generic tracking domains, which helps boost email deliverability rates.
Segment and personalize: Tailor your messages to specific audience segments to increase engagement and reduce spam complaints.
Ensure your DMARC, SPF, and DKIM records are correctly configured for your sending domains. This authentication is crucial.
Use a custom tracking domain (CNAME) within your sales engagement platform to align tracking links with your primary domain.
Segment your audience and personalize emails heavily to reduce the perception of bulk sending.
Start with smaller sending volumes and gradually increase, especially for new domains or IPs.
Regularly clean your email lists to remove inactive or invalid addresses, reducing bounces and spam trap hits.
Common pitfalls
Relying solely on sales platforms' default settings without custom domain configuration for tracking.
Sending large volumes of emails to unengaged recipients or purchased lists, leading to high complaint rates.
Ignoring bounce messages and deliverability reports, missing critical signals of sender reputation decline.
Over-automating email content to the point where it lacks personalization and reads like a template.
Not monitoring for blocklist (blacklist) listings of your sending IP or domain.
Expert tips
"Inspect your email headers meticulously when comparing native Gmail sends to sales tool sends; look for subtle differences in `X-Mailer` or `Received` headers."
"Test your emails regularly using an email deliverability tester to see how they perform across different mailbox providers."
"Implement a DMARC policy with reporting to gain visibility into your email authentication results and identify sending anomalies."
"Understand that mailbox providers value human interaction; excessive automation can negate the benefits of strong authentication."
"Educate your sales team on the nuances of email deliverability beyond just getting a 'sent' confirmation."
Marketer view
A marketer from Email Geeks says that the specific setup details really matter for diagnosing deliverability issues.
2020-09-04 - Email Geeks
Marketer view
A marketer from Email Geeks says that wrapped links or tracking pixels from SalesLoft or Salesforce domains, which are absent in native mailbox sends, are key indicators to look for.
2020-09-04 - Email Geeks
Understanding the nuanced landscape of email deliverability
The perception that Gmail bypasses blocks faced by SalesLoft or Salesforce isn't a myth, but it's not due to a magical firewall workaround. It's a nuanced interplay of email structure, sending behavior, and mailbox provider algorithms. Automated sales tools, by their very nature, introduce elements that can signal mass sending, even when originating from a trusted domain.
To ensure your sales emails reach the inbox consistently, it's crucial to understand these underlying mechanisms. By focusing on proper authentication, minimizing automated indicators where possible, and adhering to best practices for sending volume and content, you can significantly improve your deliverability and avoid falling victim to subtle blocklists (or blacklists) and spam filters. It's about sending emails that look and feel like genuine human communication, even when powered by sophisticated tools.
Gmail account, the underlying technical characteristics of the emails differ significantly. These differences are what mailbox providers (like 
Google and 
Microsoft) analyze to determine inbox placement, or if the email gets blocked altogether. This behavior often affects sales reps' Google Workspace emails.
Google Postmaster Tools to catch issues early.
