What is IP warming and why is it important?

IP warming is the process of gradually increasing the volume of emails sent from a new IP address or domain. This helps establish a positive sender reputation with Internet Service Providers (ISPs), signaling that your emails are legitimate and wanted, and thus improving email deliverability .

Why should I be cautious with content during IP warming?

It's advisable to be cautious because IP warming is about building trust with ISPs through consistent, positive engagement. Complex or unreliable content, like poorly optimized GIFs or unsupported SVGs, can lead to negative user experiences or rendering issues, potentially damaging your sender reputation instead of building it. Maintaining a predictable sending pattern is key for best practices in IP warming strategy .

Are animated GIFs always bad for email deliverability during warming?

Animated GIFs aren't inherently bad, but they come with important considerations during IP warming. Large file sizes can slow loading, affecting user experience and potentially increasing spam complaints. Not all email clients fully support GIFs, so a strong static first frame and alt text are crucial. For more details, see our article on how GIFs impact deliverability .

Can animated SVGs be used in emails at all?

Animated SVGs are generally not recommended for email due to poor and inconsistent email client support. Many clients strip out the interactive elements or fail to render them correctly, leading to a broken user experience. Static SVGs for things like BIMI logos are supported, but only if they adhere to strict, non-animated specifications.

How do I optimize GIFs for email?

To optimize GIFs for email, aim for the smallest possible file size by limiting frames, colors, and dimensions. Use compression tools. Ensure the first frame is a clear, compelling static image that conveys the main message, as some email clients will only display this. Always include descriptive alt text for accessibility and as a fallback. Best practices for email image file sizes can provide more information.

Is it OK to use animated GIFs or SVGs in IP warming emails, and what are the considerations? - Sender reputation - Email deliverability - Knowledge base

When approaching IP warming, the primary goal is to build a positive sender reputation with internet service providers (ISPs). This involves consistently sending emails that recipients engage with, signaling that your mail is wanted and legitimate. A question I often encounter is whether it's acceptable to use animated GIFs or even SVGs in these crucial warming emails.

My initial thought usually leans towards caution. While engaging content is important, IP warming is a delicate process where any misstep can hinder your progress and potentially lead to deliverability issues. The focus should be on consistent, predictable positive engagement rather than pushing the boundaries with non-standard or heavy content.

The crucial role of IP warming

IP warming is fundamentally about proving yourself as a trustworthy sender to ISPs. It's a phase where you gradually increase your email volume, aiming for high open rates, clicks, and replies, while minimizing bounces, unsubscribes, and spam complaints. The content of your emails plays a significant role in achieving these engagement metrics.

During this critical period, ISPs closely monitor recipient behavior. Positive interactions like opens, clicks, and replies tell them your emails are valuable, while negative signals, such as deleting without opening or marking as spam, can quickly damage your emerging reputation. Therefore, every element in your warming emails should contribute positively to engagement without introducing unnecessary risks.

The goal is to establish a solid foundation of trust. Using content that might be seen as overly promotional, has large file sizes that slow loading, or doesn't render correctly in all email clients, can jeopardize this process. Maintaining a clean sending history is paramount, so any content decisions need to be made with deliverability and user experience at the forefront.

Animated GIFs in warming emails

Animated GIFs can be a powerful tool for marketing emails, adding dynamism and conveying complex ideas quickly. They can enhance user engagement by capturing attention and adding a touch of humor or excitement. This potential for increased interaction might seem appealing for IP warming, where engagement is key. However, there are significant considerations.

GIF advantages

Visual appeal: Can make emails more engaging and visually interesting.
Storytelling: Effectively convey a short narrative or demonstrate a product feature.
Call to action: Can highlight a call to action or a key message dynamically.

GIF considerations

File size: Large GIFs can significantly increase email size, leading to slower loading times, especially on mobile devices or poor network connections. This impacts user experience and potentially deliverability.
Rendering issues: Not all email clients support GIFs. Older versions of Outlook, for instance, only display the first frame. You must ensure the first frame conveys the entire message, a concept discussed further by Emma on their blog.
Accessibility: Flashing or rapidly changing GIFs can be problematic for users with photosensitive epilepsy or visual impairments. Always include descriptive alt text.

If you choose to use GIFs, keep them short, loop them sparingly, and optimize their file size. A static fallback image is non-negotiable, ensuring your message is conveyed even when the animation doesn't play. For more insights into how GIFs affect email open rates and deliverability, it's worth reviewing the best practices.

SVGs in warming emails

SVGs (Scalable Vector Graphics) are typically not well-supported for animation directly within email clients. While SVGs offer crisp, scalable images at small file sizes, their interactive or animated features often rely on scripting or external stylesheets that email clients strip out for security reasons. This makes them highly unreliable for email campaigns, let alone for IP warming.

The main technical hurdle is inconsistent email client rendering. Unlike web browsers, email clients have varying degrees of HTML and CSS support, and animated SVGs fall into a category of features that are frequently unsupported or cause unpredictable rendering. During IP warming, you need consistent, positive engagement signals, and broken or unrendered content can quickly lead to recipients marking your emails as spam, which can get you on a blacklist (or blocklist).

Why SVG animation is generally a bad idea for email

Security concerns: Interactive or animated SVGs often rely on embedded JavaScript or complex CSS, which email clients typically strip out or block due to security risks. This prevents the animation from playing and can distort the email layout.
Inconsistent support: While some modern email clients might offer partial SVG support, it's far from universal, especially for animated versions. This means your animated SVG content could render as a broken image or not at all for a significant portion of your audience.
Deliverability risk: Content that fails to render correctly or causes a poor user experience is more likely to be marked as spam, which is detrimental during IP warming. Even when using image-only emails you need to use best practices.

It's important to distinguish animated SVGs from the static SVG files used for Brand Indicators for Message Identification (BIMI) logos. BIMI-supported SVGs are highly constrained, requiring specific formatting and static content, precisely because animated or interactive elements are not permitted. If you're exploring BIMI, understand that BIMI logos cannot be animated, reinforcing the general non-viability of animated SVGs in email.

Technical considerations for visual content

Regardless of whether you use GIFs or stick to static images, technical optimization is paramount. The size of your email, significantly influenced by images, can affect loading times and, consequently, user engagement. Slow-loading emails are frustrating and can lead to quick deletions, negatively impacting your sender reputation during warming.

Always prioritize image compression and consider how images are hosted. External hosting is common, but you need reliable content delivery networks (CDNs) to ensure fast load times. For images, always use descriptive alt text. This is crucial for accessibility, allowing screen readers to describe the image content. It also serves as a fallback when images are blocked or don't load, which is a common occurrence in many email clients by default, impacting email deliverability. Mailchimp provides good guidance on this.

You can include alt text in your HTML like this:

HTML with alt texthtml

<img src="https://example.com/image.gif" alt="A short, descriptive alt text for the image" width="600" height="400">

Optimizing image file sizes and making design tradeoffs for user engagement are crucial for deliverability success. This table outlines the common image formats and their suitability:

Image format	Typical use	Email client support	Considerations for IP warming
GIF	Animated graphics, short video clips	Gmail, Apple Mail, most webmail. Limited support in Outlook (first frame only).	Use sparingly, optimize size, ensure critical message is in first frame and alt text is included. Avoid multiple heavy GIFs.
JPG/JPEG	Photographs, complex images with many colors	Universal support.	Good for rich visual content. Optimize compression to balance quality and file size. Essential for protecting deliverability for image-only emails.
PNG	Logos, icons, images with transparent backgrounds	Universal support.	Ideal for sharp graphics and transparency. Optimize file size, especially for larger images, as they can be heavier than JPGs.

Navigating content choices during warming

During IP warming, I recommend a conservative approach to email content. Simplicity and consistency are your allies. Focus on building trust and demonstrating positive engagement patterns with standard, well-supported content that reliably renders across all email clients. This includes prioritizing clear, concise text and appropriately sized static images.

Views from the trenches

Best practices

Ensure any animated GIFs are highly optimized for file size to prevent slow loading times.

Always include a strong, static first frame for GIFs that conveys the full message for clients that don't support animation.

Thoroughly test email rendering across a wide range of email clients before sending, paying close attention to animated content.

Prioritize clear and concise messaging over complex visual effects during the critical warming phase.

Common pitfalls

Using large, unoptimized GIFs that increase email load times and negatively impact user experience.

Assuming animated content will render consistently across all email clients, leading to broken layouts or missing information.

Embedding animated SVGs or other non-standard interactive elements, which are highly unsupported and risky.

Focusing too much on flashy visuals rather than core engagement metrics like opens and clicks during warming.

Expert tips

For IP warming, consistent positive engagement is key. Simple, reliable content is often more effective than complex animations.

If using GIFs, ensure the content provides real value and doesn't just add unnecessary weight or distraction.

Consider the recipient's perspective: will this animation enhance their experience or potentially cause frustration?

Always include robust alt text for all images, including GIFs, to ensure accessibility and message delivery when images are blocked.

Marketer view

Unless it's significantly larger than your typical email content, the file size of animated elements shouldn't inherently cause issues during IP warming.

2020-10-02 - Email Geeks

Marketer view

The actual size of embedded images often impacts user experience, particularly load times, more than the email's raw size in the context of deliverability.

2020-10-02 - Email Geeks

Prioritizing reliability for warming success

For IP warming, the safest and most effective strategy is to prioritize consistent positive engagement and reliable content delivery. While animated GIFs can technically be used, they come with caveats regarding file size, rendering consistency, and accessibility. Animated SVGs, on the other hand, are generally not suitable due to lack of email client support and potential security issues.

Focus on a gradual ramp-up of your email volume with clean, well-optimized content that consistently lands in the inbox and encourages user interaction. This foundational approach will best set your sender reputation up for long-term success.