Do you have a specific PHP mailer you are using or will it be the default mail function? Maybe you don't really need specifics on that part so let me know if you don't know or it won't matter for what you are asking here. There will be steps to this process that are the same no matter what mailer is used but the actual mail step will REALLY depend on those details. Please clarify this so I can provide specifics and even code.
You have to use a domain. There is no way around that. Now it could be a 3rd parties but then you run the real risk, in my opinion, of having the message discounted or mistrusted by some because the sender isn't obviously you. The "factors" I mentioned which you didn't respond to should be a key in making this decision though. In some cases a 3rd party is fine but others it won't be. No matter which you use though you need to make sure you don't do things that make it seem like you should be blacklisted. Since a domain has to be used if you do get blacklisted you will have a problem, whether it is your domain or the one you are using. The more suspicious you are with the domain and sender the more likely some mail admin will blacklist you. It is always recommended to use a trustworthy domain and servers because others will often give you the benefit of a doubt for first offenses.
>> there are many email address such as bounces1234 <<
I don't really know what you mean by that.
bol
