It’s frustrating when problems occur with email. Perhaps you’ve just bought a brand-new domain and related email hosting, but Mail on OS X won’t send or receive email to the account. Or maybe Mail’s been working fine for months but has inexplicably started throwing up all kinds of error messages.

Troubleshooting email is tough, because although the problems are usually easily explained (I can’t send email! I can’t receive email!), the culprit might be one or more of any number of causes. In this article, we run through a number of possible fixes that we’ve found handy when OS X Mail suddenly becomes less reliable than the average courier service.


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1. Check you have a web connection

Before you do anything further, ensure your web connection is live. This might seem a very obvious tip, but it’s easily overlooked. Fire up Safari and see if you can load a web page you’ve not visited today. If you’ve another device on your network, check whether that can connect. If your connection’s down, power-cycle your router. If that doesn’t work, check your line’s status with your ISP. If the connection’s working on, say, an iPhone but not your Mac, cycle OS X’s web connection by disabling and re-enabling Wi-Fi and see whether that helps.

2. Check your account details

Open Mail’s preferences and click Accounts. Carefully check through all your account details, especially your email address, incoming server details and outgoing server details. Your password will be hidden, but you can always retype it if you wish. Note that depending on the details provided to you by your email host and/or ISP, you might need to define a specific port number in the Advanced tab, and/or turn on SSL for secure connections. Such details can change, and if you only have years-old details for email servers, call whoever’s hosting it or check their online support to see if you need to update anything. (Should you make any changes, Mail will ask to save them once you move away from the current account by clicking a different account, selecting another preferences tab, or closing the preferences window.)


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3. Check the recipient address

If an address is entirely malformed (which can happen due to typos or OS X autofill issues), it may still appear to send but then get bounced by the server, or it’ll fail more quickly and you’ll immediately see an error message. Check the address, retyping it if necessary.

4. Examine attachments

If an email takes an age to send and then fails, you might have attachment issues. Service providers sometimes place limits on file-sizes that are sent and received. We’ve found maximums can be as low as 10 MB, which isn’t much in an age of online media and high-quality digital photography. Should this happen, try sending an email to the same address without an attachment. If that works, use a file-sharing service to send the attachment instead, such as Dropbox or WeTransfer.

See also: OS X Mavericks review

5. Check SMTP settings

If Mail errors out and mentions SMTP settings, that’s to do with the server that’s used to send email. Some ISPs only allow you to use their SMTP server if you’re logged into your broadband at home. Other services require authorisation (as in, your username/password) for security reasons. Settings are found in the aforementioned Accounts pane. From the Outgoing Mail Server (SMTP) menu, select Edit SMTP Server List. Here, you can select servers you use and check relevant details; authentication settings are found in the Advanced tab.

6. Check your server’s not blacklisted

Spam is a nuisance and ISPs regularly get blacklisted/spam-trapped by other ISPs, enterprise servers or a user’s own spam settings. If you’re finding email is arriving with some people but stubbornly refusing to arrive with a specific contact, politely ask them to check their spam folder, or corporate spam filters if they work on a machine at a company’s premises. Should none of that be the case, the company whose SMTP server you use might be getting blocked, and its support team will be able to tell you. (Unfortunately, the solution is usually to wait until the block is removed, or find another SMTP server to use.)

Trouble receiving email

7. Send yourself a message

This might sound bonkers, but if you’ve not had any email in all day and are just feeling a bit paranoid, send yourself a message. If it arrives, chances are that everything’s OK. Well, apart from the fact you’re now clearly being ostracised by everyone you ever knew.

8. Check with your provider

If you’ve checked your settings and Mail still won’t bring down all your email, go to Window > Mail Connection Doctor. That will provide an indication of the status of your accounts. If Mail cannot connect to the server, Quit and restart the app, and then try again ten minutes later. If Mail still won’t connect, contact your email host and see if the service is down or whether your settings are out of date.

See also: OS X Mavericks tips

9. Turn it off and on again

Mail on OS X is occasionally flaky with IMAP, not pulling down all messages that it should. We’ve often found new messages arriving on our iPad that the Mac remains blissfully unaware of. A quit and restart of Mail sometimes fixes this. If not, try going to Mailbox > Take All Accounts Offline and then Mailbox > Get All New Mail. Another option is to select the mailbox and go to Mailbox > Rebuild. (Rebuilds can take some time if you’ve many messages held on the remote email server, so try the other fixes first.)

10. Check your quota

Depending on your account type, you may have a storage quota. This is even the case for Gmail, although you might not realise it. Select a mailbox in the sidebar and then click the Action button at the bottom of the sidebar (it looks like a cog) and then Get Account info. You’ll see listed your various mailboxes, how much space they’re taking up, and the total available to you. If you’re at your quota, you’ll need to delete messages held on the server or pay your provider to increase your storage allowance.


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