How can my friend bypass the spam filter?
Our spam filters are extremely reliable, but in rare cases you might find that someone who sends you mail is using a mail server that's listed in an anti-spam blocklist. This can happen if the people who run that server allow it to be mostly used to send spam, even if your correspondent is not actually a spammer.
One way to solve this problem is to use your account management control panel to completely disable spam filtering (change the spam filter setting to "Off").
However, if you do that, you will receive much more spam. If you don't wish to turn off the spam filter entirely, a better idea is to create a special forwarding address and tell the person to send to that address.
For example, if your normal address is address@example.com with the spam filter set to "High", you might create address-secret@example.com as a forwarding address that forwards to address@example.com but has the spam filter turned off.
As long as you keep the extra address secret, spammers will not find out about it: your correspondent will be able to write to you and spammers won't. Don't put the secret address on a Web page or anywhere else that a spammer might find it.