If he actually managed to hack your e-mail, I'd become scared.
He probably saw your password somewhere. Does he have access to the database of a site you are registered at? Or maybe you told someone else your password? (Doesn't even have to be him you told it to.
Just make sure you don't use the same password for many different things, create some extremely safe passwords (at least 8 characters; 3 small letters, 2 capitals, 2 numbers and 1 special character), such as 23&d0%kR{lT9. (I wouldn't use that specific one if I were you).
He doesn't DDoS, it's either a DoS or a he isn't alone. Just use a decent Firewall, though it shouldn't even be possible to DoS a regular PC (as they usually don't have any servers running)
He doesn't DDoS, it's either a DoS or a he isn't alone.
It's very rare for you to be misinformed, so just for your information, there are "DRDos" attacks, which are Distributed Redirected Denial of Services attacks. These exploit a flaw in the TCP/IP handshaking, whereby an attacker sends spoofed packets, replacing the source IP for the "target's" IP. This in turn causes the server (usually something with high bandwidth and trusted like a Google server) to think that the target is trying to create a connection, so the server agrees and sends back an ACK-SYN packet to create a bi-directional stream. However, as the target's PC never requested this, it drops the incoming packet after calculating (realising) it's not needed. But because the server is expecting a response and doesn't get it, it assumes the packet never made it to the destination and so sends out another. This multiplies the initial spoof packet into four (default setting) legitimate packets from a well known server, something that usually passes most software firewall filtering (even though some firewalls like Outpost have an awareness to packet flooding and will temporarily ban an IP until it stops).
By using this method and specifiying a selection of well known trusted servers, the attacker can multiply their outbound packets by four and not get any bandwith issues as none of the responding packets are returning, meaning one attacker can quite easily take down a site of much greater magnitude and can remain highly anonymous if he changes the source MAC of the spoofed packet as well.
On more issues raised:
1: "Hacking" e-mail is usually done by not "hacking" at all (Hacking is bad terminology created from misunderstanding. The real word is "Cracking" which is short for "Network Cracking".) Usually, the attacker finds out plenty of personal information about their target and simply guesses or resets the password (on mail providers who don't use second e-mails for authentication). To actually crack Gmail, Hotmail or Yahoo is completely unfeasable without a full team of dedicated crackers. I think the answer to this is as stated, make a damn good password. Uppercase, lowercase and numbers. Special characters too if the system allows it.
2: Your other "hack" issues come from him having your e-mail access. From there, he can go to most sites, use the info he has on you to reset the password and authenticate it with his access to your mail.
3: Keyloggers are usually a first step in the cracking process, but they are simply another method of accumulating information on your target. The advantage is that you get to understand your target's style of language and even their process of password creation, so it starts the process, but it's merely a key to unlock the door, you got to raid the house yet.
4: I do not adocate cracking in any way. I merely discuss it to broaden understanding of how people get attacked. Use this knowledge to set up adequate defence, not to learn "how to hack" *pukes a little*
I have never heard nor read about such DoS attacks, even though most of the times I try to study the subject before saying anything about it. Thank you for your correction and explanation.
I searched around for a bit and there's quite little to find about it at first sight. Only a few lines at the English Wikipedia (http://en.wikipedia.org/wiki/Denial-of-service_attack#Reflected_attack), nothing about it in other languages I speak. It's a pretty interesting subject, I might study it a bit better in the future.
Your first point underneath your raised issues was my reason to say I'd become scared if the guy had actually hacked into his mail.ru email account.
@oxytamine, I am indeed a huge noob in hacking, cracking and whatever is related, but I do know that simply downloading a program after a Google search without even knowing exactly what the program does can under no circumstance be called hacking.
Yet I wonder why you'd think that I only know something about keyloggers? Speaking about any other form of hacking was at the moment I wrote that fully irrelevant, so what is the reason for your personal attack?
Where do you see personal attack at you? By the way, there is much difference between cracking and hacking, and as Psytechnic said, hacking e-mails is often a cracking and he is right. But when I read that after hacker had cracked up e-mail and then he got all the information... My eyes streamed. Do you guys even know what Telnet is? He could hack his PC via Telnet, and newbie factis699 thought it's all came out from e-mail, eh.
TheHProject, hey, badass, your words are nothing without proofs. Hack me.
oxytamine don't behave like Super Ultra Giga master because all the hackers can hack your PC. And TheHProject, please, don't hack him because i do not think he do anything bad to you.