Strange thunderbird sending problem... [solved]

oldman talbotscott at
Fri Aug 12 16:29:02 UTC 2005

Duncan Lithgow wrote:

> Tony Nelson wrote:
>> At 7:31 PM +0200 8/11/05, Duncan Lithgow wrote:
>>> I've started getting this error in thunderbird, I thought I'd ask if
>>> anyone has seen this before...
>>> "An error occured while sending mail. The mail server responded: 
>>> unknown
>>> user. Please verify that your email address is correct in your Mail
>>> preferences and try again."
>>> It only happend sometimes and I'm not sure what the pattern is. Anyone
>>> have an idea, and no it's not my Mail preference - it works fine 
>>> most of
>>> the time.
>>> SElinux is disabled, and setting smtp as a trusted service didn't help
>>> (i've set it back again)
>> I expect that you aren't sending through your own SMTP server, but 
>> through
>> a server provided by your ISP or MSP.  This might be an authentication
>> issue with them.  In my case, I'm using (the default) POP before SMTP 
>> hack,
>> where if I've checked mail "recently", I'm allowed to send mail.  If I
>> haven't checked mail "recently" I get a scary error message that I'm
>> unknown.
>> If you are using some more sophisticated authentication, such as SMTP 
>> AUTH,
>> this probably isn't your problem.
>> ____________________________________________________________________
>> TonyN.:'                       <mailto:tonynelson at>
>>      '                              <>
> I've found the problem. Oddly enough it's one of the addresses in the 
> email I tried to send. Why it didn't just send them all out and let me 
> collect the bounced failures I don't know... I've spoken to the guy 
> with the address and got a valid address from him.
> Still, odd problem.
    I wonder if the "problem" isn't your mail provider (ISP?).  Perhaps 
the address you had was so mal-formed that the ISP cold make no sense of 
it, and bounced the entire transaction.  I think that would happen if, 
for instance you had no "@" in the address, which is different than 
having an address that looks complete, but does not exist ( in this case 
the ISP would not find out about the address 'til the mail was bounced).


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