E mail File Sizes: Are Your Pictures & HTML Information Too Large?

July 28, 2025

Greater isn’t all the time higher for electronic mail entrepreneurs – particularly in terms of electronic mail file sizes. Attempting to stuff giant photographs or ship huge HTML information can harm your electronic mail engagement and deliverability.

So, how huge is simply too huge for electronic mail file sizes? Is it time you set your electronic mail campaigns on a kilobyte-restricted food plan? Listed below are some greatest practices to get the scale photographs and HTML code good.

What can we imply by electronic mail file measurement?

You may be shocked to find out how low the tipping level is relating to file measurement and deliverability. Giant electronic mail information can severely influence your alternative to hit the inbox – not the most effective search for an electronic mail marketer hungry for fulfillment.

However what impacts the scale of those emails? Properly, after we speak about limiting file sizes in electronic mail, we’re referring to considered one of two issues:

• Pictures: The photographs, logos, photographs, and branding that make your electronic mail campaigns pop.
• HTML code: The constructing blocks and reside textual content contained in your electronic mail advertising campaigns.

So, what are some greatest practices electronic mail entrepreneurs and electronic mail designers can comply with?

Picture measurement greatest practices for electronic mail entrepreneurs

We suggest that you just all the time goal for a minimum of a 60/40 text-to-image ratio to maximise deliverability and maintain your photographs below 200KB.

Analysis by E mail on Acid additionally discovered that varied picture sizes, starting from 16KB to 696KB, had no discernible influence on deliverability. However this doesn’t provide you with carte blanche to throw numerous huge photographs into the combo.

Giant photographs can influence electronic mail load time, leading to your subscribers deleting your electronic mail earlier than it has been downloaded. Keep in mind, the common individual receives 121 emails per day– we gained’t need to waste time on emails that take quite a lot of seconds to render.

Giant photographs also can eat invaluable megabytes in restricted cellular information plans. Suppose you’re focusing on subscribers in a demographic the place pay-as-you-go cellular expertise is the first supply of electronic mail entry (assume college students, low-income households, older demographics, and subscribers in lots of rising economies). In that case, they gained’t thanks for these slow-loading, data-hungry campaigns.

It’s additionally essential to keep in mind that emails consisting of giant photographs and little or no reside textual content can increase a purple flag with the spam filters. Sadly, many unscrupulous senders will attempt to circumnavigate spam filters by hiding doubtful content material utilizing graphic representations of textual content that can not be machine-read.

HTML file measurement greatest practices for electronic mail designers

In contrast to picture measurement, HTML file measurement actually does appear to influence electronic mail deliverability. When conducting the check, our associates at E mail on Acid created a sequence of HTML emails ranging in measurement from simply 15KB to an enormous 650KB.

Maybe unsurprisingly, the information that have been lower than 100KB landed within the inbox with completely no issues. Nonetheless, deliverability turned a difficulty because the file measurement crept above 100KB. It is because the assorted spam filters employed throughout the inbox atmosphere view any pointless code in an electronic mail as probably harmful, possibly appearing as a conduit for viruses and malware.

At simply 110KB, these emails began failing in opposition to a number of spam filters. These included spam filters employed by some huge hitters within the electronic mail eco-system, together with Apple Mail 5, 6, and seven, Google Apps, Outlook 2007 and 2010, and Yahoo. Make no mistake, in case your emails aren’t reaching these inboxes, a substantial variety of your subscribers won’t ever see your campaigns.

In case your HTML electronic mail information are greater than 100KB in measurement, your design workforce can take the next steps to cut back HTML file measurement:

• Much less is unquestionably extra: Look to take away any pointless areas, carriage returns, or feedback in your HTML.
• Suppose substance over type: Take away any redundant or pointless kinds out of your code.
• Get to the purpose with a killer CTA: Do you really want a lot element in your emails? E mail advertising greatest practices have all the time highlighted the advantages of directing subscribers out of the inbox and onto a touchdown web page as rapidly as doable.

E mail clipping will minimize your campaigns quick

Deliverability isn’t the one situation referring to file measurement. For instance, sending extra-large emails might lead to emails being truncated in particular electronic mail inboxes. This follow is named “electronic mail clipping” and is often seen within the Gmail and iOS environments. A clipped electronic mail will show a preview of your marketing campaign and immediate your subscriber to obtain the entire electronic mail.

Whereas a clipped electronic mail isn’t a deliverability situation, it’s undoubtedly an engagement situation. That is very true when your CTA is omitted out of your edited marketing campaign. Necessary content material might be hidden from view and it will add an additional click on to your subscriber journey.

Gmail electronic mail clipping: forestall it

Gmail has tight requirements in terms of electronic mail sizes: Any electronic mail bigger than 102KB can and can be clipped. This implies your subscribers might be left with solely a partial rendering of your electronic mail and essential info might be hidden at first. Except your recipients click on on the inconspicuous hyperlink that Gmail offers to see the entire electronic mail, all of your exhausting work might be… nicely, minimize quick.

The unhealthy information is there’s no technique to forestall Gmail electronic mail clipping aside from lowering your electronic mail file measurement.

Optimize your emails with Mailjet

Giant electronic mail photographs and HTML information can influence your marketing campaign deliverability and might probably have an effect on engagement too, making the e-mail expertise somewhat bit extra irritating to your subscribers.

These greatest practices will provide help to get the scale of your emails good, however when you’re searching for to maximise your campaigns additional, we’ve obtained simply the software you want. With Mailjet’s E mail Previews, you may examine your electronic mail campaigns in opposition to deliverability and design points throughout a number of electronic mail inbox shoppers. This fashion, you might be assured that your electronic mail campaigns won’t be snarled up by spam filters and arrive exactly as supposed. What extra may you ask for?

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This weblog submit is an up to date model of the submit “E mail file sizes: how huge is simply too huge?”, printed on the Mailjet weblog in March, 2022.

Creator:
Beatriz Redondo Tejedor

Beatriz Redondo Tejedor is the Sr. Supervisor of Model and Content material Advertising and marketing at Sinch E mail. She is our content material advertising chief, resident Ravenclaw, and technique developer for our rising world content material workforce and types. She writes concerning the ins and outs of electronic mail, and the cultural and enterprise influence of growing insurance policies.