he is harassing me by calling me
Change your phone number or contact your service provider about how to block his calls.
emailing me 5 times per day
. . .
He's emailed me at least 300 times in the last 6 months, and if I block his email addresses, he seems to just make new ones and gets his friends to email me too
Block his and his friends' e-mail addresses and/or change YOUR e-mail address or simply delete anything they send you without reading it.
emailing me at work
Speak to whomever manages the e-mail system for your employer about blocking his e-mail address.
trying to contact my friends
Saying that he is "trying to contact [your] friends" implies that he has not been successful (otherwise, you'd have said he is "contacting my friends," as opposed to "trying to contact"). That being the case, unsuccessful attempts to contact persons other than yourself hardly constitute harassment of you.
sending my family members Christmas gifts
How exactly does "sending [your] family members Christmas gifts" (something which obviously would have happened four months ago) constitute harassment of you?
sending me things by mail to my work address etc.
You are, of course, free to throw anything from him directly in the trash. One would assume that he will eventually grow tired of paying whatever it costs to ship these things internationally.
Is there anything I can do about this?
There is no legal remedy available to you that will be any better than the practical suggestions above.