Add attachments
You can include photos, documents, and more when you write messages.
When you attach images or PDF documents, you can mark them up in Mail before you send your message.
Add photos and other files
Do any of the following:
Drag files from the desktop, the Finder, or an app into your message.
Click the Attach button
in the toolbar, locate a file (you may need to click the sidebar button 
to see additional folders), select it, then click Choose File.For photos, you can click the Photo Browser button
in the toolbar, then drag a photo into your message.
By default, Mail inserts images at their actual size. If different sizes are available, you can choose one from the pop-up menu located on the right side of the message header.
Send large attachments using Mail Drop
You can use Mail Drop to send files that exceed the maximum size allowed by your email account provider. Mail Drop uploads large attachments to iCloud, where theyβre encrypted and stored for up to 30 days.
If you have an iCloud account and youβre signed in to iCloud when you click Send, Mail automatically sends the attachments using Mail Drop. Mail Drop attachments donβt count against your iCloud storage.
If you donβt have an iCloud account, or if youβre not signed in, Mail asks you whether to use Mail Drop (to always use Mail Drop select βDonβt ask again for this accountβ).
If a recipient uses Mail in OS X v10.10 or later, the attachments are included in your message. For other recipients, your message includes links for downloading the attachments, and their expiration date.
You can turn Mail Drop on or off for an account. Choose Mail > Preferences, click Accounts, select the account, click Advanced, then select or deselect βSend large attachments with Mail Drop.β
For more information about Mail Drop, see the Apple Support article Mail Drop limits.
Put attachments at the end of messages
For the current message: Choose Edit > Attachments > Insert Attachments at End of Message.
For all messages: From the Message viewer, choose Edit > Attachments > Always Insert Attachments at End of Message (a checkmark shows itβs on).
Include or exclude attachments in replies
Include original attachments in a reply: In the toolbar of the message window, click the Include Attachment button
or choose Edit > Attachments > Include Original Attachments in Reply (a checkmark shows itβs on).Exclude original attachments in a reply: In the toolbar of the message window, click the Exclude Attachment button
or choose Message > Remove Attachments (a checkmark shows itβs on).Include original attachments in all replies: From the Message viewer, choose Edit > Attachments > Include Original Attachments in Reply (a checkmark shows itβs on).
Send attachments to Windows users
Follow these suggestions:
Make sure you send Windows-friendly attachments. To do so for all messages, from the Message viewer choose Edit > Attachments, then make sure Always Send Windows-Friendly Attachments is selected (it has a checkmark). For a specific message youβre writing, click the Attach button
in the toolbar of the message window, then make sure Send Windows-Friendly Attachments is selected (if you donβt see this checkbox, click Options in the bottom corner).Instead of sending a Pages, Keynote, or Numbers document, you can export the document as a PDF, then send the PDF.
Use filename extensions (such as .docx for a Microsoft Word document).
If the recipient sees two attachments (such as βMyFileβ and β._MyFileβ), the recipient can ignore the file with the underscore (such as β._MyFileβ).
To display an attachment (such as a one-page PDF document or an image) as an icon, Control-click the attachment in your message, then choose View as Icon. To show the attachment again, Control-click it, then choose View in Place.
If the message size shown on the left side of the message header is red, the attachments are causing your message to exceed size limits set by your email account provider. Try reducing the number or size of attachments or use Mail Drop.