error 0x800CCC65 503 valid rcpt command must preced data?

[JD1179]

We have about 8 computers in our office, everyone has their own email address
through our webhost, (e-mail address removed), (e-mail address removed) etc etc.
And only 1 computer has any sort of trouble sending email through outlook.
Although this has only become a recent issue, nothing that is "changed" to
correct it ever fixes it, or if it is fixed it is very temporary. Ive called
my web host and they just run me through the same settings that haven't
changed and sometimes it works other times it doesnt.

Is there a setting or something in outlook that might be causing this little
glitch, or something to look for on the PC. Antivirus brings back a clean
report, so as far as that goes, I think we are set.

The error popping up is. Error 0x800CCC65, the server responded 503 valid
RCPT command must precede data.

Any help in trouble shooting this issue will be greatly appreciated as this
really is getting annoying and old.

 

[Roady [MVP]]

If you have a virus scanner that integrates with Outlook, disable this
integration and try again.

Additionally you can check if your SMTP is configured to use authentication.

 

[JD1179]

I havent had a chance to check on the AV integration yet on the PC having
issues. I do know however that the problem is isolated to that computer.
Although there is 1 other PC having its own issues but a totally different
error altogether, Error 0x800CCC0F - Sending and Recieving reported error :
connection to the server was interupted. Heh, the people here in the office
keep blaming our Hosting service, but it isnt them. Because I can send and
recieve using any account on my PC... It is only these 2 PCs

The thing that is really buggin me is that nothing has changed, other than
our DNS being pointed to a new host, and that has no effect since all of the
other email accounts tied into the same host / server have no issues at all.
Even as far as anti-virus goes, they have all the same settings as they
always have had.

I looked through some other links and looked through the help sections, but
Im afraid it is going to come down to some "advanced" trouble shooting since
it just isnt making sense. Anyone that hears the situation or looks at it
scratches their head just as much.....