If you want to send fake emails to prank friends and family, there are a number of online services worth exploring. Each service has slightly different features and use cases, some will create a fake email address for you, while others actually help you write a slick email.
Note: Today, major email services have more stringent Sender Policy Framework (SPF) policies to verify sender legitimacy. For this reason, some anonymous emails may be rejected due to unknown email addresses.

Send Anonymous Email is a web application that allows you to send emails while hiding the real sender. The website claims to have successfully sent more than 10 million anonymous emails. Regardless of whether that number is correct or not, the platform gets its job done effectively.
In terms of features, Send Anonymous Email has a pretty good text editor. You can add text, embed images, edit source code, and adjust style and formatting. However, you cannot change the color and font of the text.
The site also hides some features behind a premium paywall, such as customizing sender addresses. Without registration, recipients will see emails from “Anonymousemail” and the platform's standard email address.

So the recipient will know the email came from an automated mail generator, but at least they won't know it's you. Additionally, because this is a valid email address, the SPF filter will not block the message. However, if you want to determine the sender's address, you can pay $59 for an annual subscription. As a premium user, you can also add attachments and track email impressions.
It should be noted that Send Anonymous Email takes a serious stance towards abuse of its services. According to the company's terms, legal action may be taken if you exploit the website to threaten or harass others, misrepresent an organization, or other fraudulent activities.

Emkei's Mailer may have a simple text editor, but the site offers full customizations for sending messages. You can choose From Name, From Email, To, Subject and Message.
Another significant difference between Send Anonymous Email and Emkei's Mailer is attachment support, with support capacity up to 25MB.
Emkei's Mailer hosts a plaintext editor and an HTML editor for composing messages. Therefore, this application is simple to write a short line but can also be deployed when you want to make a fake email message look more convincing.
The downside to Emkei's Mailer is that your emails don't always reach the intended recipient. Because Emkei's Mailer sends messages from unknown email addresses you create, some email services may reject them due to their SPF policies.

Anonymouse is another website that allows you to send emails from a fake address. With the AnonEmail service, this website generates a random fake email address for you, which you can use to send your prank emails.
To increase anonymity, Anonymouse will randomly delay your sent emails for up to 12 hours. This way, you can send a fake email to your friends in the same room, and your target prank victim won't immediately suspect you when they receive the email much later.
Like Emkei's Mailer, there is a risk of Anonymouse emails being rejected due to containing a fake address. Furthermore, it takes up to 12 hours to find out whether your note was sent or not.

ZMail offers a unique way to prank via email. This is the only service on this list that works through a desktop application instead of a web application. But you don't need to worry about viruses and malware. ZMail is open source, meaning anyone can inspect the code to ensure it is secure.
However, there are still limitations here. This app is only available on Windows, so Mac users will have to use one of the web apps listed. Additionally, iPhone users can search for dedicated iPhone apps to prank friends through the App Store.

Unlike the other sites on this list, Letter Generator won't actually send you anything, but it does support another indispensable step in the prank process – figuring out what you're going to say. You can use it to create an attractive letter using topics and keywords of your choice.
This site is perfect when you're not sure what to write in your prank email. Pair this app with one of the email services above and you'll have a fun joke at your fingertips.
Letter Generator's categories include love letters, notices to homeowners and even templates for writing to local politicians. Letter Generator is completely free and there is no limit to the number of letters you can create.
It's important to be responsible when sending anonymous emails. Services that allow sending fake emails can be easily abused. Pretending to be someone you are not in cyberspace raises ethical and moral questions that you should consider when using these platforms, even if the intention is harmless. Depending on the content of your message (and the actions the recipient takes based on it), there may even be legal consequences.
Fake emails can bring joy to family and friends as long as you proceed with caution. Of course, don't send teasing emails that can cause serious consequences, sadness or panic. And it should be emphasized that you should not impersonate the police or other emergency services. If you're worried about fake emails, you can always use one of these quirky prank sites to trick your friends the next time you go out.