Does Email size And Loading Speed Affect Email Deliverability?

Email Marketing | November 29, 2019

Optimising email deliverability depends on a lot of critical factors. One needs to consider the spam filets, sender's reputation, blacklists, trigger words, etc. everything needs to be taken care of. Often, certain essential factors, like email size and loading speeds, are overlooked when it comes to overall email deliverability. The size and speed of your email do play a critical role in deciding whether the email will reach your customer's inbox or not.

Email between the sizes of 15KB to 100KB is considered suitable for deliverability. When the average loading speed of emails is less than 2 seconds, it makes for excellent email deliverability too. However, your internet connection speeds matter too, and average email load speeds are dependent on it. If you can make sure your email hits these figures, then your email will surely land in your subscriber's inbox. You can take assistance from an Email marketing company in Mumbai for running these golden figures. And here's everything you need to know about email size and loading speeds:

Email size affecting factors:

1) Attachments:

Attachments are encoded files that do not affect the body size of the email. Usually, all attachments are included in the overall email limit. Large attachments are often considered as harmful, therefore, may cause your email to land up in the spam folder. So, make sure all your email attachments are below the size limit of 10MB, along with individual attachment size not exceeding 2MB. The best way to send attachments will be uploading it to the cloud and putting a link to it, thereby increasing your click-through and open rates.

2) Images:

Another essential factor which affects the email's size is images. Choosing the right image can make a significant impact on your email. The safest email size is 100KB, and if it goes even slightly higher than 100, your email will end up in the spam folder. If you are using webmail providers, it is critical to maintaining the email size below 100KB. Here's how you can do it:

  • -Use PNG images instead of JPG. PNG images are lighter and can optimise images better
  • -Do not use images without text. If your email has images without any text, the probability of it landing in the spam folder rises.

3) Encoding:

Multipurpose Internet Mail (MIME) extensions extend the email format to support text in character sets. All emails across the globe are transmitted through Simple Mail Transfer Protocol (SMTP) in MIME format. This encoding adds a 33% size to the email. Therefore, do keep this coding in mind when you send an email. Apart from coding, message headers, signatures and formatting also affect the email size. An email marketing company can help you out with the encoding services.

Email download speed affecting factors:

1) A large number of images:

A separate request goes to the server every time you add a picture in your email. Therefore, replace images with elements like styled text, CSS, Unicode characters etc.

2) Print optimised images:

Print optimised images are massive in size, some reaching 10MB in size. Such images slow down email download speed by a large margin. It is better to opt to save images from the web rather than going for print optimised images.

3) White space:

Carrying a lot of unnecessary white space can slow down overall download speed. Counter this by positioning the image through HTML. This can help reduce the image size to a great extent.

4) Including a large chunk of messages:

Instead of including every piece of content in one slab, use precise, concise and to-the-point content. This helps in reducing the load and also keeping the audience interested in your email.


The size of the email and the email download speeds are inversely proportional to each other. Lowering the size of the email results in faster download speed and vice versa. You can improve the email deliverability rate by paying attention to these components. If you need help with such issues, consider hiring an email marketing company like ValueHits. Such marketing agencies work dedicatedly to make sure your every email reaches your audience and keeps the email quality high, always. If you would like to know more about these services, feel free to dial-up and give us a call or visit our website.

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Hardik Mody

Hardik Mody is a Senior Manager in Digital Marketing. He plans and coordinates the marketing activities of ValueHits, a full-service Digital Marketing Agency in Mumbai, India. With his experience and Expert knowledge in the field, he identifies potential customers and develops marketing campaigns. Also, he is efficient enough to meet the client’s requirements and well-organized in handling multiple tasks.