Answer
Tar-pitting, also known as teergrubing, is a method of slowing responses to SMTP commands. Many servers implement this as a means of deterring spammers from using their servers. In reality it is much better to use effective filters and rules to detect and stop any potential spam attacks.
Tar pitting occurs when you post to a remote SMTP server, and it responds to the POST server commands very slowly, tying up your POST threads and reducing the efficiency of the POST service. This normally takes the form of them sending multi-line SMTP responses with one line being sent every minute or two – this could go on for hours.
GMS will automatically disconnect from any remote SMTP server that it detects is attempting tar-pitting. Any messages queued for that server will be retried at a later time.
Keywords:tar-pitting connections teergrubing post