[X4U] mail -- already fried

[m senft]

Am running 10.4.0. I have our email accounts with our ISP
(Cablevision's Optonline). I plugged in the account info for the four
a various number of times (but, for example, did the main account at
least 8-10 times).

An anomaly pops up: In certain ituations, usually when the app refuses
to send mail -- which it always does and is the problem -- it gives
the server name followed by a colon and the account name e.g. the part
of the email address before the @.

Neither Opt's TS nor Apple's has an answer. Rather, Apple's was to do
an archive + install reinstall -- didn't work.

Anyone have any answers? Solutions?

Thanks,

    Mitchell