Before someone opens your email, they see two things – the subject line and the preheader. These two short pieces of text decide whether your email gets opened or ignored. This document explains what subject lines and preheaders are, how to write them well, and how to use features like merge tags and emojis to make your emails feel more personal.

What Is an email subject line? 

The subject line is the short title of your email. It appears in bold in your reader’s inbox, right next to your sender name. Think of it like the headline of a newspaper article. It needs to grab attention and tell the reader what the email is about, and in just a few words.

What is a preheader? 

The preheader is the short line of text that appears just after the subject line in most email clients like Gmail, Outlook, and Apple Mail. It gives readers a little more detail about what’s inside the email. When used well, it works together with your subject line to encourage opens. For example,

Subject: Flash sale ends tonight, Emma!

Preheader: Up to 50% off your favourite products — don’t miss out

Using merge tags to personalise your emails 

Merge tags let you automatically insert personal details like a contact’s first name, company, or location directly into your subject line. Instead of sending the same generic subject line to everyone, you can make each email feel like it was written just for that person.

How merge tags work 

A merge tag is a short placeholder written in a special format. When the email is sent, Zoho Campaigns replaces the tag with the actual information from your contact list. For example, if you use the merge tag “First name” in a subject line like “Your favorite items are on sale, First name!”, a recipient whose first name is John will see it as “Your favorite items are on sale, John!”.

Zoho Campaigns lets you use the following merge tags in your email subject line:

• First name

• Last name

• Company name

 How to add a merge tag in the subject line 

To add a merge tag in the email subject line:

1. Click the “@” icon next to the subject field.

2. Select the required merge tag from the dropdown.

Using emojis in subject lines 

Emojis can help your email stand out in a crowded inbox. They add a visual element and can quickly communicate the tone or topic of your email.

Why use emojis? 

Using emojis in your subject line can make your emails more engaging and noticeable in the inbox. They:

• Catch the eye in a crowded inbox

• Can replace words and save space

• Make your brand feel more friendly and approachable

• Can improve open rates when used in the right context

How to add emojis 

To add emojis to your email subject line, click the emoji icon next to the subject field and select the emoji you want to include.

Best practices 

• Keep the subject line short (40–60 characters) so it doesn’t get cut off, especially on mobile devices

• Be clear and specific about what the email is about, as clarity works better than clever or vague wording

• Mention deadlines or limited-time offers only when relevant to create urgency

• Ask questions when appropriate to spark curiosity and encourage opens

• Avoid spam trigger words like “FREE” or excessive punctuation, as they can affect deliverability

• Make sure the subject line matches the email content to maintain trust

• Use different subject line styles to keep your emails fresh and engaging

• Pair your subject line with a meaningful preheader. It is not ideal to leave it blank or repeat the same text

• Use emojis thoughtfully. You may use one or two, and ensure they match the tone, and add value

• Avoid using ALL CAPS, overusing emojis, or making the subject line look spammy

• Test your subject line (and emojis, if used) across devices and email clients before sending