Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected. I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was '.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required', Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

Tools | Accounts | Mail | Properties | Servers. Is: My Server Requires
Authentication checked? The error message suggests that it should be.
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" Bob wrote in message
...
Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected. I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer
overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was '.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required',
Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

Thanks for response, Bruce.
I have already phoned Comcast and these were correct: POP3;
mail.comcast.net; smtp.comcast.net. Is that what is meant by "authentication
checked"?
Bob

"Bruce Hagen" wrote:

Tools | Accounts | Mail | Properties | Servers. Is: My Server Requires
Authentication checked? The error message suggests that it should be.
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" Bob wrote in message
...
Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected. I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer
overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was '.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required',
Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

No, it is a box you check.

Tools | Accounts | Mail | Properties | Servers. Is: My Server Requires
Authentication checked?

I don't know if this is the answer, just something to try since the error
message mentions it.

Your address is being rejected by Comcast. You may find some information
here as well.

Comcast FAQs:
http://www.comcast.net/help/faq/index.jsp?faq=Hot117481
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" wrote in message
...
Thanks for response, Bruce.
I have already phoned Comcast and these were correct: POP3;
mail.comcast.net; smtp.comcast.net. Is that what is meant by
"authentication
checked"?
Bob

"Bruce Hagen" wrote:

Tools | Accounts | Mail | Properties | Servers. Is: My Server Requires
Authentication checked? The error message suggests that it should be.
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" Bob wrote in message
...
Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected.
I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer
overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft
error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was
'.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required',
Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

On the tools..accounts..mail..properties..server tab make sure the 'My
Server Requires Authentication' box is checked.

"Bob W" wrote in message
...
Thanks for response, Bruce.
I have already phoned Comcast and these were correct: POP3;
mail.comcast.net; smtp.comcast.net. Is that what is meant by
"authentication
checked"?
Bob

"Bruce Hagen" wrote:

Tools | Accounts | Mail | Properties | Servers. Is: My Server Requires
Authentication checked? The error message suggests that it should be.
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" Bob wrote in message
...
Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected.
I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer
overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft
error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was
'.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required',
Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

Thank you, thank you Bruce and Ricky!! Checking the "Authentication" box
fixed it. I wonder why it wasn't working before since I have done nothing
with my accounts? I don't know whether the box was checked or not before the
problem. Can in arbitrarily uncheck or work without it being checked?
Again, your help was appriciated! Have a great day. Bob

"Ricky" wrote:

On the tools..accounts..mail..properties..server tab make sure the 'My
Server Requires Authentication' box is checked.

"Bob W" wrote in message
...
Thanks for response, Bruce.
I have already phoned Comcast and these were correct: POP3;
mail.comcast.net; smtp.comcast.net. Is that what is meant by
"authentication
checked"?
Bob

"Bruce Hagen" wrote:

Tools | Accounts | Mail | Properties | Servers. Is: My Server Requires
Authentication checked? The error message suggests that it should be.
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" Bob wrote in message
...
Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected.
I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer
overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft
error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was
'.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required',
Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

Bob, I have had the exact same problem for 3 days now. I just went in and
UNCHECKED "My Server Requires Authentication" and all of my outgoing mail
just left! Hope it works for you too.

"Bob W" wrote:

Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected. I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was '.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required', Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

You're welcome. Comcast has a habit of changing things fairly often, but I
don't know if this is recent or not. If you do find that some settings
become unchecked seemingly on their own, keep this in mind.

Settings that become unchecked may be caused by one or more of the following
programs. There are probably others that will do it as well.

Ad-aware's Ad-Watch
IBM Access Connections
McAfee VirusScan and/or Antispyware
Norton AV
Spyware Blaster
Spybot Tools IE Tweaks
Spybot- Teatimer
Spysweeper
Spyware Doctor
Windows Defender
Zone Alarm (free) 6.5 Reported to be fixed in later versions.

In the case of Zone Alarm 6.5 or Norton 2007 it actually has to be
uninstalled. Make sure the Windows Firewall is turned on until you
reinstall Zone Alarm.

Boot into Safe Mode with Networking and try the change.
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" wrote in message
...
Thank you, thank you Bruce and Ricky!! Checking the "Authentication" box
fixed it. I wonder why it wasn't working before since I have done nothing
with my accounts? I don't know whether the box was checked or not before
the
problem. Can in arbitrarily uncheck or work without it being checked?
Again, your help was appriciated! Have a great day. Bob

"Ricky" wrote:

On the tools..accounts..mail..properties..server tab make sure the 'My
Server Requires Authentication' box is checked.

"Bob W" wrote in message
...
Thanks for response, Bruce.
I have already phoned Comcast and these were correct: POP3;
mail.comcast.net; smtp.comcast.net. Is that what is meant by
"authentication
checked"?
Bob

"Bruce Hagen" wrote:

Tools | Accounts | Mail | Properties | Servers. Is: My Server Requires
Authentication checked? The error message suggests that it should be.
--
Bruce Hagen
MS-MVP Outlook Express
Imperial Beach, CA


"Bob W" Bob wrote in message
...
Outlook Express has been used for a long time with no problems and
nor
alterations have been made. 4 days ago the sent emails were
rejected.
I
turned off computer over night and it worked again the next day.
Then,
yesterday, the sent emails were rejected and I shut off computer
overnight.
Error problem still exists. Receiving emails works OK. I can send
OK
through webmail at Comcast, but not from OE. Here is the Microsoft
error
message:

The message could not be sent because the server rejected the
sender's
e-mail address. The sender's e-mail address was
'.
Subject 'testing', Account: 'Bob Wilmot', Server:
'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication
required',
Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

Peggy, it is funny that your "unchecking" and my "checking" both worked. Is
Comcast your ISP? bw

"Peggy W." wrote:

Bob, I have had the exact same problem for 3 days now. I just went in and
UNCHECKED "My Server Requires Authentication" and all of my outgoing mail
just left! Hope it works for you too.

"Bob W" wrote:

Outlook Express has been used for a long time with no problems and nor
alterations have been made. 4 days ago the sent emails were rejected. I
turned off computer over night and it worked again the next day. Then,
yesterday, the sent emails were rejected and I shut off computer overnight.
Error problem still exists. Receiving emails works OK. I can send OK
through webmail at Comcast, but not from OE. Here is the Microsoft error
message:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was '.
Subject 'testing', Account: 'Bob Wilmot', Server: 'smtp.comcast.net',
Protocol: SMTP, Server Response: '550 5.1.0 Authentication required', Port:
25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78

"Bob W" wrote in message
...
Checking the "Authentication" box fixed it.
I wonder why it wasn't [was?] working before since I have done
nothing
with my accounts?

E-mail providers change their requirements. Some are slow to
implement anti-spam measures. Many now want to ensure you have
permission to use their resources rather than a spammer trying to hide
on another domain while using someone else's mail server.

For info on off-domain port 25 (SMTP) traffic blocked to thwart spam
from spamming or infected customers, read:

http://www.commercestreet.com/Blocking_Port_25.htm
http://help.yahoo.com/help/us/mail/pop/pop-38.html

http://www.postcastserver.com/help/P..._Blocking.aspx
http://www.aota.net/Troubleshooting/port25.php4
http://www.spamhaus.org/faq/answers....0Spam%20Issues...
http://www.findarticles.com/p/articl.../ai_ziff129473

http://www.google.com/search?q=%2Bbl...2BSMTP+%2Bspam

One, some, or all of the following could have changed or are being
implemented:

- Your ISP (the network to which you connect) requires you use their
mail servers. They do not permit you crossing their network to use an
off-domain mail server over which they have no control and cannot log
e-mail traffic that uses their network. Usually this means they block
e-mail traffic using port 25 that targets an off-domain network;
however, it is also possible with protocol analyzers to detect traffic
is for e-mail and block that traffic. This is probably why Gmail opted
to force SSL connects because they use ports other than the standard
of 110 for POP3 and 25 for SMTP since everyone using Gmail is trying
to cross their ISP's network to get at an off-domain mail server.

- The targeted mail server does not allow off-domain connections (or
requires non-standard setup of SSL, different port numbers, and/or SPA
to make off-domain connections). You are crossing your ISP's network
to reach the targeted mail servers, but to those mail servers you are
not on their network when trying to connect to those mail servers
(i.e., you are off-domain to them). You will need to check what
settings AOL requires for off-domain connections which could be
different than for on-domain connections. My ISP (Comcast) is like
that: while on their network, you connect to their mail servers using
110 for POP3 and 25 for SMTP but when coming from off their domain
then you need to use SSL, 995 for POP3, 465 for SMTP, and also use SPA
to connect to their mail servers.

- Some e-mail providers require that you send before you receive. Many
e-mail clients receive first and then send. As a result, the
expectation is that the mail server will reuse the login for the
receive session also for the send session but the send session has to
be within a short time after the login for the receive session (not
from when the receive session ends). If there are lots of mails or
delays, too much time elapses and those login credentials for the
receive session are lost so you cannot send. The cure is to enter your
login credentials for the send session (SMTP) or to change the order
of sessions within your e-mail client (send and then receive). Maybe I
missed it but I don't see an option in OE (so it probably isn't there
in WLM) to change the order of the sessions (i.e., to receive first
and then send, or to send first and then receive). Instead and when
defining e-mail accounts in any e-mail client, I always configure the
SMTP server settings to require authentication and then specify the
same login credentials as for the POP3 server (rather than say to
reuse them). This means I have to twice enter my login credentials:
once for the POP3 configuration and again for the SMTP configuration.

Just because you don't change anything doesn't mean your e-mail
provider cannot.