You can customize the toolbar in the Finder and many apps. You can add buttons, spaces and other controls. Some apps have a large selection of buttons you can add. You can also revert to the default set easily. See what is available in the Finder, Mail, Pages and other apps.
One formatting option missing in Mac mail is the ability to highlight text by adding a background color to a text selection. This is useful when you want to point out a passage in a response and is commonly using in Windows email clients. While there is no way to do it with standard text styling in Mail, you can create a custom style by copying and pasting an example from Pages, creating a style, and then applying that style later on in other messages.
When you type and email address in Mail, you will get some suggestions that include your Contacts and also a list of previous recipients. Some of these addresses may be old or ones you don't wish to see anymore. You can delete them using the Previous Recipients list in Mail.
You can use your own sounds for alerts in macOS Sierra and Mail. You'll need to convert the sounds to AIF format and put them in the Library folder. Then these custom sounds will show up after restarting System Preferences or Mail.
With Mac Mail you can view individual messages or group them together in conversations. Which you use is a personal preference. With conversations you can view all of the messages sent back and forth between two or more people about a single subject. This makes following responses easier.
You can sign PDF documents in the Preview app and in Mail. You save your signature using either the trackpad or your Mac's camera. You can then insert that signature in any spot in the PDF. It then becomes a permanent part of that PDF just as if you had printed out the document, signed it, and then scanned it back in. You can do the same in Mail, but only the copy sent will contain the signature.
In addition to sending email 'to' someone, you can also include additional email addresses in the CD and BCC fields. CC is a way to send copies of your messages to people that need to know the information, but don't need to respond. BCC is a good way to send messages to people without sharing their email address with others.
Mail in El Capitan allows you to easily work with multiple messages in full screen mode. You can minimize the composition window and return to it. You can also put multiple messages into the composition window and select them using the titles of the messages at the top.
A new feature of Mail in El Capitan is the ability to swipe across a message using your Mac's trackpad to access some common functions. This is similar to how Mail in iOS works. You can mark a message as Read or Unread, or delete it. You can also change the delete option to archive. This even works for messages not currently selected.
When you compose a new message in Mail, you are usually spending a very short amount of time in the Mail composition window and it is easy to miss some of the features. At the top of the window you can use various buttons and add more. You can also change the fields available to you, such as adding or removing CC and BCC fields and even a REPLY-TO field. In the message body area, you can use styling and also mark up images and PDFs.
Text Replacement is a built-in function on your Mac that allows you to automatically replace one sequence of characters with another. You can use them to fix common typos, make it easier to type long phases, or even allows you to insert longer passages you commonly use when writing. They can also help when trying to type special characters or emoji. Text Replacement works in most apps though some have special settings.
You can filter junk mail in the Apple Mail app, but you should first try to prevent spam email from even getting past your server. If you use a good transportable email address, like Gmail, you'll get most of your junk mail filtered out before it gets to your Mac. Apple Mail can act as a last line of defense if you set up junk mail filtering in the preferences. You can also add your own filters for reoccurring spam email in Gmail and in Apple Mail. If you no longer want to receive mail from a company you have done business with or have subscribed to, be sure to use their Unsubscribe button instead of reporting the email as junk.
With OS X Yosemite you can mark up images and PDF files right inside of the Mail composition window. This can make it easy to send notes and revisions back and forth between people working on projects. You can also add signatures to PDFs easily in a reply. The same tools are available in the Preview app outside of Mail. In the future, Apple and third-parties can add more extensions like Markup.
When you reply to a message in Mail, you can quote the original message to make your reply clearer. You can quote the entire message, but it usually make more sense to only quote a portion of it. You can also edit the quotes and place your reply between portions of quoted text. Learning how to use quoting properly can help you send more concise, clear and professional email replies.
An often-requested feature of Mac Mail is the ability to tag messages with keywords. While full tagging ability isn't included in Mail, you can add colored flags to messages to help you organize them. You can even rename the flags to make them more useful. But for true tagging ability, you would need a third-party extension like MailTags.
When you type a quote or apostrophe symbol on your Mac, it will usually automatically convert to the curly version. However, you can control when this happens on a per-app basis. You can also make exceptions to the process while typing. See examples in TextEdit, Pages and Mail.
Learn about some of the actions in Automator that control the Calendar and Mail app. Build a workflow that will search your events, summarize them as text, and convert that text to an audio file. Then Mail can send it as an email message.
Using the Mail app on your Mac you can get a special alert when an email from a specific sender arrives. This can be a sound, notification, icon bounce or even a special color for the email in your inbox. To do this, learn to use Mail rules. A rule can identify a new message and then apply an action to it. You can also have messages forwarded to another email address.
You can type Emoji characters on your iPhone, iPad or Mac and add them to your text messages, email messages or documents. Emoji characters are color characters with small images like smiling faces, map symbols, hearts, and so on. On the iPhone and iPad you need to enable the Emoji keyboard to easily type these. On the Mac, you need to turn on your character viewer.
Mac Mail has a feature that allows you to use colorful email templates. There are many to choose from, and you can buy more from third-party companies. You can also create your own through a variety of methods.