Already 12 years have passed since I created my Gmail account back in 2007. That was the time when I first needed a more professional email address that includes my real name, not a nickname that I used for gaming or MySpace (Wow, I instantly felt old when MySpace came to my mind).

These days most young people create their first email address when they get their first smartphone. I bet that the majority of these kids create Gmail addresses because they already know about Google by the age of 8-10, which is not surprising at all.

Gmail has more than 1.5 Billion active users

Gmail has over 1.5 Billion active users officially (October 2018) and, as such, serves as the primary email address for most people on the Globe.

Maybe only a Chinese email provider could do better than Google, but email is dead there. Actually, it never born at all (they use WeChat for nearly everything).
For the rest of the world, email is here to stay. And Gmail is the biggest player in the field, and as such, it’s a prevalent topic in every email marketer community.

No matter how often it comes up, I couldn’t find a resource that lists out everything an email marketer should know about Gmail, so I decided to dive deep into the topic for you guys.
In this full guide to Gmail, we cover:

  • Subject line length in Gmail
  • Preview text length in Gmail
  • Gmail’s Promotions Tab
  • Clipped Messages in Gmail
  • Images in Gmail
  • Forwarded Emails in Gmail
  • Anchor Links in Gmail
  • Custom Fonts & Google Fonts in Gmail
  • AMP for Email

Subject Line Length in Gmail

Most people view emails on iPhones and Gmail, so you’ll need to optimize your subject line for both.

Most resources online suggest that email subject lines should be between 41 and 70 characters for this reason, but I was a bit skeptical about the 40 character mark already.

I ran some tests that included a Galaxy A40, an iPhone 8, and an iPhone XR and found that the safest subject line length for Gmail App is 30 characters only.

Here are the screenshots from each device.

Gmail App on Galaxy A40

(2,340 x 1,080 px resolution)

galaxy a40 gmail subject line length

Gmail on iPhone 6 – 8

(1,334 x 750 px resolution)

iphone 6-8 gmail subject line length

Native Mail App on iPhone 6 – 8

(1,334 x 750 px resolution) / dark mode

iphone 6-8 native email app subject line length

Outlook App on iPhone 6 – 8

(1,334 x 750 px resolution) / dark mode

Gmail App on iPhone XR

(1,792 x 828 px resolution)

Native Mail App on iPhone XR

(1,792 x 828 px resolution)

iphone xr natie mail app subject line length

Of course, the Gmail webmail can accompany much longer subject lines, especially when viewed on a full HD screen, where even 100+ characters could fit in one line.
But still, I wouldn’t advise you to go any longer than 70 characters or so.

The fact that only 30 characters can fit into one line on the Gmail App doesn’t mean that you can’t write longer subject lines, of course.  Just be prepared to deliver the essence of your subject line in the first 30 characters for better engagement.

Preview Text Length in Gmail

In Gmail’s web client, the preview text length depends mostly on your subject line length.

For example, with a 40 character long subject line, 57 characters of preview text were visible on my screen in Gmail (screen resolution was 1440×900 when I tested).

Mobile email clients typically show less of your preheader text, that’s why it is advised to keep your preview text in the 30 to 55 characters range.

There’s a little preview text hack spreading in the email marketing community that can help you make your preview text include only what you really want to be there.

You only need to add a chain of zero-width joiners and non-breaking spaces after the preview text that you want to be displayed.

This way, only the given text shows up in the email client and no other content from your email. The downside of using this hack is that it increases email size a bit, depending on how many times you add these placeholders to your email code. So use this with caution and test how many extra placeholders are needed for you to fill the preview text space.

Is the Promotions Tab Heaven or Hell for Marketing Emails?

Gmail introduced the tabbed inbox over 6 years ago (in May 2013).  However, the debate over whether or not the tabbed inbox is good or bad from a marketing perspective hasn’t been settled yet.

There are many marketers looking to find a way to get their messages delivered to the Primary tab instead of Promotions.  Although there are ways to make that happen, I believe that the right place for your marketing emails is definitely the Promotions tab and not the Primary inbox.


  • Because Gmail users look for marketing emails under the Promotions tab, that’s just a simple habit Google helped them to create over the years.
  • Let your subscribers choose when to view your marketing emails. This way, you can make sure that they are prepared to make a purchasing decision when they actually spend time browsing through the Promotional emails.
  • There’s a higher chance to be marked as SPAM with your marketing email if it ends up in the Primary inbox.
  • According to Returnpath’s study from 2017, the average read rate for messages in the Promotions tab is 19.2%, while the read rate in the primary inbox is 22%. This 12% difference is not something that should motivate you to fight for a bit more attention. Instead, focus your efforts on making your messages as relevant to the receiver as possible (using personalized content).
  • Almost half of the people using Gmail with the tabbed inbox check their Promotions tab at least once a day, while 70% check it weekly.

I personally advise you to give up on getting your marketing emails delivered to the Primary inbox, and

  • Stop asking your subscribers to add your Sender’s email address to their Gmail contacts.
  • Don’t ask all subscribers to move your email to the Primary inbox. This sounds like an easy shortcut to get more attention, but do you really think it’s a good idea to beg for some extra attention from everybody? If you want to add this type of email to your funnel, make sure to identify your most loyal customers, who have already purchased from you at least 3-4 times, and then ask.

litmus gmail promotions tab builder

  • Take advantage of Google Annotations to make your emails look better in the Promotions Tab. Annotations show images, discounts, codes, even before a subscriber opens your email. This handy little tool from Litmus helps you make more of your emails.

Gmail Clips Messages

Gmail clips any email that’s weight exceeds 102 KB- “officially.” However, based on email geeks’ tests, the limit is not exactly 102 KB. It’s actually less than that. So aim for a lighter email weight, around 98 KB.
Keep in mind that only the weight of the email HTML matters, not the images that are included in your emails via links.  Those play a significant role in email loading time but don’t affect clipping at all.

[Message clipped] is something that often causes headaches for email marketers, even in large companies like Twitter. For example, I got this digest email from them recently, and it was clipped by Gmail well before the end, although it only included highlights of 6 popular tweets from the people I follow.

gmail clips even twitter's emails occasionally

You’ll easily hit the 102 KB limit with a long email that features a series of products. It’s especially hard to be prepared for this if you send automated emails that include dynamic content and are generated on the fly – for example, abandoned cart emails.

Gmail Loads Images Automatically

Google introduced image caching in Gmail at the end of 2013, and since then, images are shown by default in all emails unless a user decides to turn off images.
This means that 95% of your Gmail subscribers see all images in your emails when opened because only very few people change default settings in reality.

Gmail Breaks Emails When Forwarded

We occasionally receive feedback from some users who use Chamaileon for email design, saying that their emails get messed up when they forward them from their Gmail to one of their colleagues.

We explain to them that, no matter what we do, Gmail messes up the email HTML when it’s forwarded and causes the email to lose some styles that were initially there and might even break in some cases. There is no known hack to prevent email forwards from breaking the email, so for now, this is something we just need to deal with as email marketers.

Thankfully, it is not a massive issue for subscribers because they don’t really forward emails.

We see that email forwards mostly happen for in-house review and approval purposes. That’s why we developed software features like the test email sending and the share link that help with the review/approval processes. According to Litmus’s Viral Email Report from 2015, the Forward-to-Open Rate was only in the 1.91% – 5.04% range, even for the most viral emails while emails in the 50th percentile were only forwarded at a 0.16%-0.30% rate.

It means that the fact that Gmail breaks fancy HTML emails when forwarded only influences a small fraction of email campaigns.

To know if you fall into that lucky group, you need to make sure that you include “Forward to a Friend” call-to-action in your emails because only then can your ESP track if your email was forwarded to somebody or not.

I browsed through 50 promotional emails from random big brands like Fitbit, Bose, Google, Asana, and National Geographic on Really Good Emails to check how many include the “Forward to a Friend” option, and found that only 6% had it in the email.

Of course, this was not a large-scale study, but it already shows that only a minority of email marketers believe that their emails are viral enough to be forwarded, so in my opinion, you don’t need to worry too much about the fact that Gmail breaks forwarded emails, but still, it’s something you should know.

Anchor Links Don’t Work in Gmail on iOS

The good news is that Anchor links do work in Gmail when used on browsers or Android devices. The bad news is that it doesn’t work in many other email clients.


I wouldn’t consider it a good practice as emails are not meant to be a one-stop destination with so much content that you need an anchor. Also, there is no support for it in IOS, which has a huge amount of users.

Michael Stephan

Digital Campaign Specialist


I completely agree with Michael. Generally speaking, it’s a bad practice for email marketers. But maybe, it can work for some in-house newsletters when HR knows who receives the email and what email client they use.

Gmail Doesn’t Support Custom Fonts & Google Fonts

How ironic is that?

No matter how reliable source Google Fonts is, Gmail still won’t display most Google Fonts.  Instead, only web-safe fonts show. So make sure to either use web-safe fonts in your email or test how your email looks in Gmail.

Only Google Sans and Roboto render properly in Gmail, and they only render because these fonts are included in the actual user interface and load automatically.

Gmail Supports AMP for Email

AMP is an open-source technology designed to improve web content performance and is used to add some interactivity to emails. The AMP properties are not added to email HTML, but as a separate part in the final sent email, so many email service providers are not prepared for it yet.

Gmail was the fastest to implement AMP for email support and most likely because they wanted to make the use of Google Drive and Gsuite even smoother for their users. AMP for email provides marketers with the option to add interactive elements to their emails, but for now, only Gmail, and support AMP for email.

Yahoo! Mail also announced so that they are planning to support AMP and we can expect other webmail providers to join the list, so most likely we’ll be able to use more and more interactive elements in our emails by the end of 2020.

At least 25% of subscribers view emails in Gmail, so you should care!

No matter how unhappy you are with the fact that your emails end up in the Promotions tab or that your message might be clipped at around 102 KB in size, you still need to deal with it because at least 25% read emails in Gmail according to Litmus.

Keep in mind the above-listed issues with Gmail, and always make sure to send a test email from your email design software or email service provider to a Gmail account before pushing the “SEND” button.