HTML Email Signature Troubleshooting Guide

Have you created an email signature in HTML, only to find that the signature is inconsistent in different email clients? There’s some good news and some bad news. The good news is that many of the problems can be fixed by implementing the solutions in this email signature troubleshooting guide. The bad news is that not all of them can be fixed.

If you really get stuck, you could always give our email signature generator a try. After all, its free to use.

Creating email signatures is much harder than it needs to be. There are so many HTML formatting issues that are unique to email signatures and they just don’t come up for the most part, even in Internet Explorer (if you are a web developer, you’ll know what I mean!)

We’re compiling an ever-expanding list of common and hard to diagnose formatting issues so that if you are making a signature only to find that it is riddled with problems, the solution should be on this page!

If you have an email signature with a formatting problem that you can’t find, let us know and we’ll be happy to try to find the cause. It will help us to make this guide all-encompassing.

Email Signature Has a Gap Below Images

In most/all email clients:

Solution: Add a line height style attribute to the containing table data element <td style="line-height:0px; {add other inline styles here as needed} ">

This would not work if there is text within the same <td> element but text should not be there in the first place since it should be in it’s own <td> element, separate from the image.

Only in Gmail:

Solution: Haven't found one

In testing, if you send an email from Outlook 2016 to Gmail and back again, I haven’t found a way to remove the gap when viewing the email signature in gmail.

email signature gap below images

Email Signature Images Changing Size

Solution: Remove the horizontal and vertical resolution attributes from the image properties.

First, view the properties of the image (in windows right click > properties > details), be sure that the horizontal and vertical resolution are not set. You will need to use an image processing tool to remove this data from the images. This is because Microsoft Outlook scales the images using the values in these fields. So if the email recipient has their Windows desktop set to 100% scaling, and the image is 96dpi, there will be no scaling and everything will be okay. However, if the desktop is set to 110% scaling, a different value is needed or Outlook will still scale the image.

Microsoft Surface devices are known to be problematic with email signatures as they automatically set the Windows scaling to around 200% to compensate for the size of the screen on the unit. This can have a huge impact on email signatures not displaying correctly and they will often look skewed if Windows scaling is set to anything more or less than 100%.

email signature image scaling

Email Signature Images Aren’t Displayed at the Correct Size

Solution: Set the image height and width attributes on the <img> tag without units such as px. For example <img height="60" width="120">.

Be sure that these attributes match the actual dimensions of the image in pixels. So if your image is 10 pixels tall, the image tag should have a height attribute equal to just “10” without any units.

Email Signature Images Are Blurry (aren’t Clear)

Solution: Ensure your image resolution is set to 96dpi. Find the correct image dimensions for the final signature, then create a scaled final image in reliable software instead of scaling the image in html.

If images don’t look as clear as they should after changing its dimensions, there are a few things that need to be considered. Firstly, be sure that the original image is high quality, if not, of course you would need to get a good high-quality image before proceeding. After that, follow these instructions to rule out compression or save quality problems. We will stick to web applications to get the job done.

email signature image dimensions

The image should now be clear and can be used in your email signature. If it’s not, it’s most likely that the quality of the original image is to blame.

Email Signature Images Being Added as Attachments

Solution: Make sure your email client is set to compose new emails in HTML format and if needed, change the email formatting on each incoming email that has been formatted in plain text / rich text format. 

Check that your exchange server is not automatically converting your outgoing emails to plain text.

Sometimes your email signature will come up in plain text and not be displayed like it was when you first created it. This happens due to the email in question being composed, or converted to plain text / rich text format. When this happens, Outlook will automatically convert any images that were in the email signature, into attachments.

Click here for more information

Email Signature Troubleshooting

Email Signature Font Changing to Times New Roman When Sent to Outlook

Solution: Ensure you put a Non-breaking space (&nbsp;) in front of the element that is getting changed in Outlook. Also, ensure that sans-serif is not the last font in the font-family or any other font property. Always have another font as the last one, otherwise Outlook will convert it to Times New Roman.

This is an issue that has been plaguing Outlook for quite some time, and it can be a very difficult problem to fix, unless you know where to look. The versions of Outlook it affects is 2007, 2010, 2013 and 2016. This also depends on the platform you are sending the email from. For example, if you send from Outlook for Mac to Outlook 2016 in Windows, the problem likely wont appear. However, if you send from Office 365 to Outlook 2016, you will notice the problem come up.

So it’s easier to understand what the problem actually is, we will first illustrate with some pictures on the right.

Notice the difference in the fonts from the original sent email signature, and the one that was received in Outlook 2016? The original email signature was sent using Arial font and Outlook converted it to Times New Roman. Thankfully, there are a few known working fixes for this issue, but the problem is that sometimes you may need to try a couple of different fixes in order to figure out which one works for you.

Original email signature in Office 365 (this is the way the signature is supposed to look like):


This is the email signature when it arrives in Outlook 2016:


Outlook Not Downloading Images Automatically in Email Messages

Solution: Set your Trust Center settings in Outlook to allow automatic download of images in email messages.

Outlook has a security feature that is enabled by default which prevents images from being automatically downloaded on all incoming emails.

Click here for more information


Gmail Email Signature Too Long Error Message

Solution: Ensure your email signature has less than around 10,000 characters and you are using Google Chrome or Internet Explorer when updating the signature in Gmail.

Gmail will give you an error message saying “Sorry, the signature for <your email address> is too long. Please try a shorter signature.” if your email signature is greater than around 10,000 characters. If your email signature has more than 10,000 characters, you will need to lower the character count for it to work with Gmail.

Gimmio’s email signature generator has signature templates that are optimized for Gmail and you can also find out the character count of your email signature before you install it.

Gmail takes all characters into account, whether it is HTML code or text. There are also a number of other factors that it uses to determine if your email signature is too large to use.

This error message may also come up if you are using Firefox, Safari or any other browser other than Google Chrome or Internet Explorer. When you copy your email signature using Firefox and Safari, some additional HTML code is included which can push your email signature over the 10,000 character limit.

Gmail Email Signature Too Long

Cannot Add or Edit Email Signature in Office 365

Solution: Edit the OWA Mailbox Policy permissions to allow Email signatures as a feature.

When trying to add an email signature to Office 365 OWA (Outlook Web Access) you may notice the Signature section is missing, greyed out, or you may see a message like “The option you chose isn’t available.”

This is because the feature is disabled in your OWA policy. There is an easy way to fix this if you have administrative rights to your Office 365.

Office365 ECP Sign In
Office365 ECP Permissions
Office365 ECP Features More Options
Office 365 ECP Features Email Signature
Office365 OWA Email Signature Not Available

Copying and Pasting an Email Signature Is Breaking the Formatting

Solution: Use Google Chrome to copy your email signature.

When creating an email signature in Gimmio (or any other email signature generator), you may get formatting problems when pasting your email signature into your email client. The most common reason for this happening is that your browser isn’t copying all of the HTML tables in the email signature.

For example, if you are using Gimmio with the Safari browser and you attempt to copy the email signature, Safari will not copy all of the HTML tables, and the formatting of the email signature will be broken when you paste it into your email client. The solution is to use Google Chrome when copying your email signature, this will ensure that all HTML tables are copied correctly.

Images Not Showing up in Your Email Signature in Apple Mail

Solution: Check to make sure the following settings are correct.

Sometimes Apple Mail might not display images in the email signature when it is shown in the signature preview window. However, when you compose a new email, the signature looks as it should (with images).

Other times, the email signature will not show images at all, even when you compose a new email. There could be various reasons for this, the most common are listed below.

  1. Mail > Preferences > Composing tab > Message format – Rich Text.
  2. Mail > Preferences > Viewing tab > Load remote content in messages – Ticked.
  3. When installing your email signature, ensure you untick the box at the bottom of the signature preview which says “Always match my default message font” as this will turn your email signature into plain text.

Thunderbird Has Red Borders Inside and Around the Email Signature

Solution: This is normal Thunderbird functionality.

Thunderbird will often show red borders inside and around the email signature when you compose a new email. Those borders will not be visible to your recipients, and your email signature will look normal to them.