2821 DATA timeouts

Hi,

RFC2821 states in section 4.5.3.2 that while the SMTP client is sending 
the messag body, it SHOULD accept up to a three-minute delay between 
each time it can send data.
With 1500-byte packets, that implies that an SMTP client SHOULD be happy 
with speeds as low as eight bytes per second (1500 bytes per three 
minutes), which strikes me as being a little on the low side... is that 
limit intentionally that low?
--Arnt