Happened to me yesterday. On a Gmail-hosted account and I still got dozens in my inbox. (Though Gmail’s spam filter is very very good, all-in-all.)
I have had my own domain for years and it had become unusable because of spam. Hosting it on Gmail has made it quite good and I often recommend it.
The important thing to keep in mind is that any spammer can send mail from your address or your domain—this doesn’t mean that they’ve hacked your site or taken control of any aspect of your mail. They can send as you, but can’t receive mail addressed to you.
If they have accessed your account, say by installing a key-logger at an Internet café where you checked your mail, or sniffed wireless traffic while on an open WiFi connection (very simple to do) then you may be in real trouble. There were a few people hit by this, where the found themselves locked out of their account while their friends received “help me, I’m trapped in a foreign country” emails, begging the friends to wire money to Western Union. (Since they have access to your whole account, they can read old mail and send very personalized mails to trick your friends and family.)
If this happens, contact your email provider immediately and have them lock the account until you can verify your identity.
When traveling, it’s best to avoid using public terminals and net café computers as they can’t be trusted—use your own. If you use open WiFi, either install a VPN (Virtual Private Network) package like HotSpot Shield (http://www.anchorfree.com/downloads/hotspot-shield/ ) or ask your company or agency to set up their own VPN.
HotspotShield is a company that encrypts all of your network traffic in exchange for inserting an ad into the top of web pages you visit. Your data passes through their servers, so it’s not exactly secure from them, so if you have truly sensitive data, you’ll need to consider that, though you will be safe from the guy at the next table running a sniffer program, capturing all of the wireless traffic, looking for passwords. (Anyone sharing the WiFi connection can do this, quite simply.)
Hope this helps.
Jim