Q: How do I block an email address in mac mail?

Mail > preferences > Rules, set mail from that address to be deleted immediately.

• Select Mail | Preferences... from the menu in Mac OS X Mail.
• Go to the Rules tab.
• Click Add Rule.
• Make the criterion read From Contains.
• Insert the email address of the person you want to block.
• From the actions, select Delete message.
• Assign a Description to the new rule.
• Close the dialog with OK.

Check the Wiki-how in the URL shown below.  Essentially, you just open the unwanted e-mail, click 'add to Contacts', then go to Settings, Messages, and Block.  Select the newly added contact.  While it doesn't say so on the device (seems set up ostensibly for phone calls and texts), the Wiki-how indicates it will also block unwanted e-mails from the blocked contact.  A follow-up below the Wiki-how indicates you needn't even keep the contact; the address remains blocked even if the contact is deleted.

Perhaps this will be simplified in iOS8.  But if not, this seems to be the way to do it.

http://m.wikihow.com/Block-an-Email-Address-on-iPhone

1Launch iPhone’s Mail app. Tap the Mail app from your iPhone’s home screen to open it.

2Open a message from an e-mail address you want to block. Once you’ve opened the Mail app, tap the message that came from the e-mail address you want to block to open it.

3View the sender details. To do this, tap the e-mail address displayed on the “From” field. This is at the top-most part of the screen. You will be able to view the sender details.

4Create a new contact. Just tap on “Create New Contact.” This option should be on the sender details window.

• Before you can block an e-mail address on your iPhone, it should first be saved on your contact list; otherwise, you won’t be able to block it at all, so you must create a new contact for the e-mail address to be blocked.
• On the following screen, type in a name for the contact you want to block.

5Add the e-mail address to your contact list. Just tap “OK” at the bottom of the screen to add it to your contact list.

THEN

1Head to your iPhone’s settings. Tap the Setting icon on your iPhone’s home screen. This will open the device’s Settings app.

2Choose the “Phone” option from the list on the Settings menu. Scroll down the Settings screen, and tap on the “Phone” option. This will display your phone settings, like your number, voicemail, and more.

Tap “Blocked” from the list of options. Here you can add contact details like the phone number or e-mail address that you want to block on your phone.

4Add a new contact to block. Tap on “Add new” on the screen. Once you tapped “Add new,” your contact list will be displayed. Scroll down the list and select the contact you want to block.

• Once you add it to the blocked list, you will no longer receive any e-mail messages from that specific sender.

This is about Apple Mail, not iOS.  Please read the question and don't hijack posts.

Actually, it worked for me.

I created a "Spam" contact and add any spam mails addresses to it. That labeled it Spam for me, but until Fred posted this, it hadn't occurred to me that it would block the emails as well. Until now, I've only been using the block function for telemarketing calls.

Thanks, Fred Thorne. Good tip.

John Zitzelberger

aka macanes

Can anyone tell me if this would delete the spammers email permanently as in if there were other computers logged in as you, would the email be deleted for them too?

Thank you for posting this! I was trying to block mail on both my OS X and iOS!

If it is an IMAP (or Exchange) account yes, as soon as the rule is processed its effect will be reflected on all clients. If it is a POP account, no.

I have someone sending harassing emails, can they be re-directed back to them?  I don't want them to think I'm receiving them, I'd like them to bounce back is that possible

Mail's bounced feature was removed.

my big pronlem is that *.xyz sends spam and scams and I get tired of seeing them in my junk folder on my iPad email. the contact block method is great for a single address but they change almost for EVERY email ... might be abc.xyz today and zozocool.xyz then todayshot.xyz or etc ... how do i keep from seeing it ???

If Apple is your email provider send the emails to Apple according to this document. 

iCloud: Why am I getting junk mail (spam)? - Apple Support

Do it for a while to give them enough samples so they can determine the source. If they can they can block it.

For domains (that part of an email address after the '@' sign) that you are confident* are always from scamie-junk origins, such as ANY email with a 'From' address that I have ever seen an email from that ends in '.xyz' (from the .xyz domain), set up a Rule (as others have posted above) as shown below:

*Be careful with this becuase it will permanently delete all emails that meet your criteria!  IE:  Do not specify to delete all emails that have a from address that 'ends with' the string '.com' -- that would result in you losing all email from good origins like '@me.com'.  Therefore, please very carefully consider what groups of from addresses you want the emails to automatically get deleted so that you do not end up missing out on important emails that you care about. 

Best of luck -- (well, it works for me anyways...)

is the rule method possible on an iPad Air iOS 9.3.1 ???