---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/sendgrid/ui/sending-email/formatting-html#article
headline: HTML Formatting Issues
description: Follow these HTML formatting guidelines to send email through Twilio SendGrid, preserve content, and fix rendering issues caused by MIME encoding and line length.
url: https://www.twilio.com/docs/sendgrid/ui/sending-email/formatting-html
inLanguage: en
dateModified: 2026-07-21T11:17:13.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# HTML Formatting Issues

Follow these guidelines to send email through Twilio SendGrid, preserve your content, and resolve issues with the HTML formatting or styling of your messages.

## Include both plaintext and HTML versions

Include both plaintext and HTML versions of your email so recipients can view the information in the mail client of their choice. If you only send HTML emails and a recipient's server or mail client blocks HTML content, they see nothing in your emails.

## Follow character limits

Keep each line of content to 78 characters or fewer, and don't exceed 998 continuous characters.

For more information on how to format email, see the [RFC 5322 formatting guidelines](https://datatracker.ietf.org/doc/html/rfc5322). (Refer to 2.1.1. Line Length Limits.)

## Troubleshoot rendering problems

Some mailers, such as Apple Mail, place Multipurpose Internet Mail Extensions (MIME) into emails automatically, which can cause the Twilio SendGrid system to not parse the boundaries correctly. If your email content doesn't render correctly, do the following:

1. Some mail clients, such as Outlook and Thunderbird, appear to insert double spacing line breaks at every line. The reason is that the 'content-transfer-encoding' in MIME is set to 'quoted-printable' which adds Carriage Return Line Feed (CRLF) line breaks to the source content of the email which are characters interpreted by these mail clients. To alleviate this problem, please do the following:

   a) If you can customize the MIME settings for your email, set the 'Content-Transfer-Encoding' to '7bit' instead of 'Quoted-Printable.'

   b) Ensure that your content follows the [line length limits](https://datatracker.ietf.org/doc/html/rfc5322).
2. Hard line breaks appear as CRLF characters in the source of an email with the character combination of " **=0D**" in the source of an email. This only happens with 'quoted-printable' (Content-Transfer-Encoding set in MIME) emails. Email clients such as Outlook and Thunderbird render these characters which results in additional breaks in the content of your emails.
3. The best possible MIME layout in your email when sending through SendGrid is as follows. It is best to reference files using separate links to download since it lowers the percentage of spam threshold for most domains you are sending to.