By the way, the host can be section in the contract or FAQ which outlines the terms of mass mailings.
Failure to follow these rules might just be "other troubles".
The two whose services were used, were the rules:
— No more than so many of the letters over a period of time.
— Another more complicated: the same limit for the period and the requirement that all the letters clearly indicated to whom there is a letter why it is sent and a description of how to unsubscribe from the mailing list (detailed instructions or a direct link to unsubscribe).