If someone says,
あなた は Chris-さん です か。
Are you Chris?
Do you answer
さん is never used (except jokingly perhaps) to refer to oneself. The same goes for other common endings such as
That's because these endings usually convey a kind of relation: for instance,
さま conveys respect,
ちゃん convey some endearment and while
さん conveys very little meaning, it does convey separation. You can't use
さん on yourself because it's pointless to specify your relation to yourself. And this is even truer for the other endings.
Unless it is some sort of elaborate joke, you should not put -さん after your name.
Maybe a story could be helpful...
Once when writing the minutes (議事録 gijiroku) of a meeting, I had to write the list of the participants at the meeting. I wrote it like this, and then sent the email.
●●さん ●●さん Wallyさん
As soon I sent this email, the reaction from my coworkers was: "LOL, he put さん to his own name". And tons of 指摘 shiteki afterwards.
So yeah, you should never put -san after your name unless you're trying to be funny. If you want to try to be funny, send an email within the mailing list to another coworker without putting -san to his name. Lots of shiteki guaranteed.