What would be the likely cause of *intermittent* 0x800ccc0f errors

[Guest]

As you can tell from frequent other panicky posts of mine, I'm having a huge
problem getting ox800ccc0f errors when sending e-mail attachments that are
"large". I have followed many, many different suggestions, but to no avail.
I think this bit of recent information may be helpful, though:

This is clearly an intermittent problem. Tonight, during one of my many
tests, I sent a file successfuly - immediately following an exit of McAfee
Security Center. (Scanning of output messages was already turned off.) In a
state of euphoria, I then successfullly sent another! However, since that
time, it has steadfastly refused to send any of my larger files, except for
one time. During all of this processing, I have made no changes to
parameters, settings, accounts, etc.

I have no mail at my mail server, so it's not a question of a full in-box
someplace.

Anybody got any bright ideas as to what to try next? FUD is clutching at my
heart...

Thanks.

 

[Guest]

Update: I uninstalled McAfee and reran my tests - all attempts to send the
attachments failed. That seems (to me, at least) to remove McAfee as a
possible culprit.

Anybody got some ideas as to what I ought to try next?

 

[Guest]

I have (tentatively) declared victory over this problem: The Outlook
conisiderations were red herrings, I think. Tcpip settings on my PC were not
optimum (in particular SackOpts and TcpMaxDataRetrnsmissions). I have
experienced no problems since setting those to 1 and (default) respectively.