Sending Attachements

[mickalo]

Hello,

I have a customer, when sending out emails, with attachements, they get the follow error message:

Your server has unexpectedly terminated the connection. Possible causes for 
this include server problems, network problems, or a long period of 
inactivity. Subject 'test', Account: 'mail.investordataexchange.com', 
Server: 'mail.investordataexchange.com', Protocol: SMTP, Server Response: 
'421 justlightening.justlightening.net SMTP incoming data timeout - closing 
connection.', Port: 26, Secure(SSL): No, Server Error: 421, Error Number: 
0x800CCC0F

according to the error code numbe, it indicates the connection is dropped. Would this be cause by excessively large attachements or is this a problem on our server? Is there some way to increase the timeout somehow ??

thx's
Mickalo