People who got their hands really wet with exchange 2007/2010 has a good amount idea about Exchange back pressure. Basically it is a kind of situation where Microsoft Exchange stops receiving emails. This is a new condition introduced in Exchange 2007 and improved in Exchange 2010 for better handling of emails.
Exchange server feels this back pressure when it is out of resources. This resource outage can be of two types 1) Disk out of space 2) High Memory utilization
See this video to understand it better.
[Video Source : www.insidetheregistry.com]
There is a third type… due to High number of Uncommitted Message Queue DB Transacts.
Not lookin at the video.. sorry on travel. I hope this is mentioned in it.
AFAIK, that won’t cause back pressure. One fair chance is that if the logs reaches their max limit/disk goes out of size due to mail queue DB, then there is a chance. But in this case it is disk space which is causing the back pressure. That means 1) and 3) are interrelated. What do you say…