I'd like to register my extreme disagreement with this method of harvesting spam! You're exploiting some one else's free service for your own gains (and according to something you said in the CB this is for your own commercial benefit, since you're doing this for work). Just because this service is for free doesn't mean it is not costing hotpop.com money for storage space and bandwidth consumed, and as far as I can see (IANAL) using their free mail account as a spam drop box violates their terms of service.

If you want to collect spam, set up a mail server yourself (or better, have it set up by someone who knows what they're doing) and pay for the hardware and bandwidth yourself.

Disclaimer: I am not affiliated with hotpop.com in any way and do not know anything about them beyond what I learnt from a quick browse of their website.