All email clients render HTML/CSS differently. When rendering HTML and CSS in emails many things impact what the end-user is going to see. These vary from client to client; browser to browser; server to server. Here are some best practices you can utilize so that your emails' coding will stay intact across different clients and platforms.
Email Layout

It is the structural elements that are laid accordingly as required it is the overall look that an email is presented. It is presented in the content body as Greetings, Headline, Content, Call to action, and Closing. Here a few points to be noted while structuring an email.

Avoid using padding or margins
Certain email clients don't support these formatting settings. For example, Outlook cannot support padding, and Hotmail cannot support margins.

These can be especially problematic when added inside of a table in either mail client.

Always use inline CSS
Most webmail clients (,, Gmail, etc) will strip CSS out when stripping the head and body tags.
Make sure you render coding very carefully so it conforms to the email client's pre-set HTML.

Avoid BR, HR, and height tags in your emails
Every browser/client has its default line-height and will default to it most of the time.

The workaround in the next bullet point below
Use Tables to create a general layout of the email
Set the width of each cell in the table.

Avoid cell spacing and padding.
Always set a "doctype" in your code
Set wrapper reset styles in "wrapper div"
This can override a browser or client's default styling of certain elements.

Be aware of text and font changes per device (mobile especially) and browsers
Mobile devices and different browsers may change the font styling to increase readability.
For example, Comic Sans is not supported on mobile devices.

Email Backgrounds

Email Background attributes are such as color, text color, font. They are the designed element that is applied to the background part of the email in supporting each other to fit perfectly in the inbox. Below is the key to note in email backgrounds.

Use the older more basic background HTML tags
"background-image" ; "bgcolor" ; "background"
Many browsers and clients experience issues when trying to support compound CSS values, so be sure to use individual values such as "background-image" and "background-repeat"
Always offer reset background colors or fall back background colors to defer to if your specific background isn't supported

Email Images

Attaching images to emails adds more efficiency. It is done through HTML coding in embedding images in the email that appears instantly as an image instead of as an attached file.

Always avoid PNG images - Try to always use either JPEG or GIF images

Always provide image dimensions

Some email clients will automatically apply their own if none are given which can lead to major issues when rendering these images in relation to spacing and alignment.

It is important to note however that some email clients will do this regardless as a default setting.

Make sure to give ALL of your images 'alt' attributes - This simple step will keep the overall sizing of your images the same across platforms. adds some pixels at the end of each image which can rearrange spacing, alignment, or padding

Use the " hack" - IMG {display:block;}. This removes the padding in and gives predictable results across many other email clients in terms of added spacing or padding to images.

Avoid 'float' tags
Outlook cannot support these tags, so SendGrid recommends using align tags. For example, .

Yahoo! has similar issues, so SendGrid recommends using align="top" for the image in question.


Many clients simply cannot support rendering video (other than GIFs) in their emails
JavaScript nor the object tag are supported in many clients or browsers and thus can't support video rendering



Email testing is very much advised, as there is no one standard for email code they might don’t fit in every mobile device due to lack of services or potential. It is suggested to run a testing email code.

Here are the testing email codes

HTML Email Checker validates the markup (HTML ,XHTML,CSS ) of HTML. Which also checks images, validates links, and accessibility, Enables easy change between HTML validation, layout view, email sending, and also categorizes the importance, with detailed information on the affected email clients. It includes all tools needed to create an instant validation result. Here is the link

Accessible-, its mission is to spread email marketing accessibility and usability, which can be the voice of users and the email marketing community. Helps in editing the code and also sets reports by analyzing campaigns for emails. Here is the link

PutsMail is another email testing platform that provides basic testing applications that are easy to test emails and improve the design of emails. Here is the link


Testing email makes sure they are delivered properly and fits in all inboxes, previews before about the time it takes to load an image in the email. Taking at most care in designing emails can go into the trash if they are ignored to test before sending them. There are plenty of email testing tools that offer services for various problems wicked in emails. Testing that can be done for the following works involved in email.

Email Previewing and validation tool
Sender Reputation tool
Deliverability checking tool
Subscribers verification tool
Subject line testings tool

Email Previewing and Validation tool :

The proper landing of email content is the main concern of every email sender, they need to be sure in the time taken to preview images. For instance, to check the images loading period, are they fit for every inbox or not are such things to be noted. Here are the recommended tools to preview and validate emails.

Litmus - It is used to preview emails in a wide variety of platforms and helps to change the code right in the platform only. It is used by most enterprise-level and one of the biggest email testing tool

Mailtrap- It ensures whether HTML code is working properly and not only that it offers a wide variety of email tests like previewing and validating the emails by using the fake servers.

Email on Acid-It is a good option for small businesses or groups, which is a kind of robust reputation. Offers previewing testing on 70 different clients on devices.

Preview My Email- It helps to double-check the code on various email clients and platforms, using multiple ways to test the email. This allows users to either upload directly or send emails to the special Preview My Email inbox.

Inbox Inspector - It allows to preview emails in more than 25 most popular clients including popular desktop sites, mobile apps, and webmail

HTML Email Check- It is a free tool in validating the markup languages for your emails and newsletters, which is also a handy tool for checking images, validating links, and accessibility.

Sender reputation tool :

Email sender reputation plays an important role in delivering emails into the receiver’s inbox.ISP (internet service provides) analyzes the email and rates the sender accordingly, analyzing the content subject involving all kinds of algorithms.

From checking spam emails to sender reputation. Here are the tools in managing the sender’s reputation and spam emails.

Mail-Tester- Used to check spam related emails. It examines them using SPF and DKIM records for keywords that indicate spam algorithms and other metrics

Sender Score- It is mostly focused on fetching the reputation of the sender with a detailed report of there reputation as a sender

Postmark- It is a tool used to get the sender score directly without sending the email to the tester link by simple copying and pasting the code into the tools easy interface

Reputation Authority- It is used to analyze the domain reputation which contains the history of the domain and recent problems.

“Litmus and Email on Acid tools also provides sender and spam checking reputation”

Deliverability checking tool :

The deliverability tool helps to recheck the emails if not sure about the sender’s reputation and spam emails. It identifies and fixes the flaws involved in deliverability.

SendForensics- SendForensics helps in examining the sender score, the content in email, spam filters, and other criteria with real-time scoring. You can set deliverability alerts to monitor email and safeguard email reputation.

Subscribers verification tool

Sending an email to an invalid address may result in bounced emails, which affects the sender’s reputation and turns bulk emails into spam emails. Subscribers verification tool helps in maintaining a clean email address that ensures to list only the valid emails It is used to have a clean email list free from duplication and invalid email addresses. It consists of the history of invalid email addresses using is easy, fast, and efficient.

DataValidation- Data validation provides a quality report of the email list that guarantees 99% of email deliverability. You required to upload or import an email list DataValidation starts analyzing the list.

Email Checker- It is a simple and straight forward email tool that helps in verifying the email list by simple copying the addresses right infield to validated the list

NeverBounce - Used to analyze and verify an email list of any size providing a validated email list.

Pabbly - Pabbly helps in removing unwanted, inactive, duplicate emails, and improves email deliverability. It offers an easy user interface with just a few clicks.

Subject Line testing tool

Subject lines place the key role in delivering emails, testing to fit the perfect subject line for each email can be challenging. But these tools help you in evaluating the weak subject line before sending your emails.

SubjectLine - The SubjectLine tool helps in analyzing the subject lines in order to avoid spammers and also suggest to increase the open rate. They make a difference by referring to data collected from its partners. It provides real-time benefits in creating subject lines.

CoSchedule’s Headline Analyzer- It is a great tool to analyze the headline for the blog which was originally developed for and also for subject lines as they both incorporate some features

Email Subject Line Grader- It helps in creating an error-free subject line including the length, grammar, and other elements like emotions. It was developed specifically to look at email subject lines.

Zurb TestSubject- Zurb TestSubject tool is used to check how the email subject line is displayed in the mobile devices. Because the information displayed might differ from device to device and client to client

Send Check It- Send Check it is a tool that checks the subject lines by testing their reading level, character, word count, and also looks for spammy words, punctuation.


Joining the above dots coding email is not simple, it is brought only through pursuing, a clear picture of what you learn from made mistakes in order to excel the list. Here are the key points to note

Know your customers.
Use a single-column layout.
Use HTML tables for the layout.
Set your width to 600px.
Double the size of your logo.
Inline your CSS.
Style the ALT text
Use a standard font.
Add media queries.
Test how your email renders across platforms.

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Author's Bio: 

I am Vignesh, doing a digital marketer.