cannot send emails through outlook express but can receive them.Get following error messageThe message could not be sent because the server rejected the sender's e-mail address. The sender's e-mail address was ....., Server: ......', Protocol: SMTP, Server Response: '451 4.3.2 Please try again later', Port: 25, Secure(SSL): No, Server Error: 451, Error Number: 0x800CCC781 person needs an answerI do too

Did this just start, or has this account never worked? That error message is usually a temporary server issue. You did omit part of the error though. If you want to munge the address, change what is before the @ sign, but not what is after it. Also, there is no need to omit the server name. It can offer clues as well.Bruce HagenMS-MVP Oct. 1, 2004 ~ Sept. 30, 2010Imperial Beach, CA

This only just started.My email address is ...@optusnet.com.au Server is mail.optusnet.com.auHave spoken to provider (Optusnet) & they say it is a microsoft problem

This only just started.My email address is ...@optusnet.com.au Server is mail.optusnet.com.auHave spoken to provider (Optusnet) & they say it is a microsoft problemAnd it is your address that is rejected, correct? Does this happen if you try to send a message to yourself?My money is on a server issue that will clear up on its own, but you can try a couple of things to eliminate it being on your end.1: Turn off e-mail scanning in your anti-virus program. It is a redundant layer of protection that eats up CPUs, slows down sending and receiving, and causes a multitude of problems such as time-outs, account setting changes and has even been responsible for loss of messages. Your up-to-date A/V program will continue to protect you sufficiently. For more, see:http://www.oehelp.com/OETips.aspx#3 Why you don't need your anti-virus to scan your emailhttp://thundercloud.net/infoave/tutorials/email-scanning/index.htmNote that for many AV programs, it may be necessary to uninstall the program and reinstall in Custom Mode and uncheck e-mail scanning when the option is offered. 2: Create a new Sent Items and Outbox.Move most of your messages out of the Inbox and then create new Outbox and Sent Items folders after you move any messages you wish to save to a local folder you create.Tools | Options | Maintenance | Store Folder will reveal the location of your Outlook Express files. Write the location down and navigate to it in Windows Explorer or, copy and paste it into Start | Run.In WinXP, Win2K & Win2K3, the OE user files (DBX and WAB) are by default marked as hidden. To view these files in Windows Explorer, you must enable Show Hidden Files and Folders under Start | Control Panel | Folder Options Icon | View, or in Windows Explorer | Tools | Folder Options | View.With OE closed, find the DBX files for the Outbox & Sent Items and delete them. New ones will be created automatically when you open OE.After you are done, follow up by compacting your folders manually while working *offline* and do it often.Click on Outlook Express at the top of the folder tree so no folders are open. Then: File | Work Offline (or double click Working Online in the Status Bar). File | Folder | Compact all folders. Don't touch anything until the compacting is completed.General precautions for Outlook Express:Do not archive mail in the Inbox or Sent Items. Create your own user defined folders and move the messages you wish to save to them. Empty Deleted Items folder daily. Although dbx files have a theoretical capacity of 2GB, I recommend about a 300MB max for less chance of corruption.Information about the maximum file size of the .dbx files that are used by Outlook Expresshttp://support.microsoft.com/?kbid=903095Bruce HagenMS-MVP Oct. 1, 2004 ~ Sept. 30, 2010Imperial Beach, CA

Thanks for your help.I had 9000 emails in my sent items box so I deleted all bar the past two year (5000 left) and I am now able to send emails.Will look at some of your other suggestions later.Regards Ray N

You're welcome & thanks for posting back. Bruce HagenMS-MVP Oct. 1, 2004 ~ Sept. 30, 2010Imperial Beach, CA