Either your domain is out of disk space, or your e-mail address itself is out. You will need to increase the amount of disk space to receive mail again.

Does it say "please enter your username and password for the following server" and you are sure you're using the correct information?

Most of our servers have a 60 checks per hour limit. If you hit this limit in any hour you'll be locked out for the rest of the hour. you will need to click > tools > options > general > and disable where it says "check for new messages every xx minutes" If you do not want to disable it just set it to check less often. keep in mind the more computers you have auto checking or checking the mail the quicker you will hit this limit.

If you can receive mail but are not able to send this means one thing.....

Your internet provider is blocking you from using anyone's outgoing mail servers but their own.
Many Australian ISP's are blocking outgoing SMTP mail servers that are not there own.
The reason they do this is to prevent you from using their internet connection for spamming purposes.
You will still be able to send emails, but only by using your ISP'S outgoing mail server.

Every ISP's outgoing mail address is different, but for the most part they will be like below

POP (incoming mail server) mail.yourdomain.com.au
SMTP (outgoing mail server) the one specified by your Internet Service Provider (bigpond, internode, optus and others)

http://tutorials.ausweb.com.au/web/Tutorials/Email-Tutorial-:-FAQ-for-Email-setup/Microsoft-Outlook-Express-Email-Tutorial/

For whatever strange or maybe silly reasons the big ISPs in sunny Australia seem to think that blocking port 25 for their clients will prevent the annoying spammers from doing their evil deeds.

AUSWEB clients can get around this and use their own SMTP mail server with us (mail.yourdomain.com.au) by following those simple steps below.

Email spam is a very frustrating reality of the online world we live in. Many tools have been developed along the way to try and combat this probelm including both server and desktop solutions. This tutorial will guide you through enabling Spam Assassin on your hosting account using your cPanel.

Microsoft Outlook is a personal information manager from Microsoft, and is part of the Microsoft Office suite. Although often used mainly as an e-mail application, it also provides a calendar, task and contact management, note taking, and a journal. This tutorial covers the configuration of Outlook to access your emails from your hosting account

Microsoft Outlook Express is an e-mail and news client bundled with certain versions of Microsoft Windows starting with Windows 95. This tutorial covers the configuration of Outlook Express to access your emails from your hosting account.

This tutorial is suitable Windows Live Mail or Windows Mail - which is a lite email client that can be downloaded as part of Microsoft's "Live" suite for use with your Windows Live ID and normal POP/IMAP based email accounts. Live Mail is available for Windows XP, Windows Vista, and Windows 7.

In This tutorial we will learn about using Mozilla Thunderbird as your email client. We will cover setting up a new account and editing an existing account.

In this tutorial you will learn how to setup Mozilla Thunderbird as an email client on your Mac OSX

What you will Need
1:- A valid email account, if you haven't created an email account yet please log into your Control Panel and set up an email account.
2:- An email client. This tutorial uses Mozilla Thunderbird, which is a free opensource email client.

Eudora is an email package that is free to download from http://www.eudora.com. Eudora has three modes -- Sponsored, Paid, and Light. Sponsored mode gives you the full-featured product, but displays ads on part of your screen. The ads are relatively unobtrusive. Paid mode gives you the same thing as Sponsored mode, without the advertisements, but you need to pay for and register it. Light mode is Eudora without the bells and whistles, but also without advertisements.

Login to webmail, after doing so copy the entire URL from your address bar.

You will now log into your cPanel and create a subdomain to go to the address you just copied, like webmail.yourdomain.com.au

And then create a redirect from the subdomain to the URL of your prefered webmail program

To login to your webmail use the following url:

http://www.yourdomain.com/webmail/

*where yourdomain.com is your domain name

Login details are your email address and password you setup in your control panel

Make sure your email client is configured correctly. Please refer to the tutorial for your particular email client for more information.

- Make sure your user name and password is all lowercase.
- Make sure you have created the email address in your control panel.
- Change the user name to the full email address. Example: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

Mailing Limits

There is an hourly limit of 500 emails per domain this limit is also applied towards mailing lists. If you send over this amount in any hour most of the e-mails will bounce back with a undeliverable error.

Many of our servers have a 60 pop checks per hour limit per email address.? If you go over this you're likely to get a wrong password error message saying login incorrect. Just wait an hour and it will automatically unlock you. to prevent this from happening again make sure to disable auto checking or at least set it to something higher such as 10 minutes.

Any mailing list larger than 2,000 will require a dedicated server solution from us. Note: dividing one large list into smaller lists to get below this limit is not allowed.

We have a maximum size of emails of 5MB and under, any email over 5MB will be automatically rejected, please use your FTP to transfer big files !

To throttle your PHPlist mail-out please go to the PHPlist forum to find guidance http://www.phplist.com , Specifically this link is showing a few appropiate solutions http://www.phplist.com/forums/viewtopic.php?t=2232

This video will show you how to setup email accounts in Incredimail.

This video will show you how to setup email accounts in Netscape.

This video will show you how to setup email accounts in Eudora.

This video will show you how to setup email accounts in Outlook.

This video will show you how to setup email accounts in Outlook Express.

This video will show you how to setup email accounts in Pegasus.

This video will show you how to setup email accounts in Thunderbird.