Outgoing spam filtering

Apparently some hostings (for example hostmysite.com) use firewalls to filter outgoing e-mails based on content.
Do you think they allowed to do so ?

I would not chance my host filtering my outgoing Email. How frustrating would it be if good email gets filtered? I would hope they would at least bounce emails back to you letting you know your email was blocked.

yes they do send it back to me

I have even turned that off on my own personal computer, in my firewall settings. The way to combat that problem is by making sure the machine is free of any and all malware. If it is, you have nothing to worry about where spam coming from you is concerned.