hum... i tried with different mail address, same result, and also sending without smtp, direct dns...
i also tried to change the time out in both my mail client and avast...
i realise now that I autozip all the attachments I send, so all are zip files
those who doesn't cause an issue are small ones (less than 100 ko)
the error is "error 5 error sending data socket error"
actually, the file progress until 99% and never reaches 100%
i tried to send attachement many times since today and despite this warning, some of them arrive...
i won't for sure change my mail client
and as i'm pretty sure of what i send, turning off outcoming scan is the easiest way....
edit setting the time out to 120 did it work... i just set it to 90 before
so problem solved... thank you again
thanks you anyway