Mail cannot connect to network (But network works)

Hi There

I'd be most thankful if any of you here could assist me with this.

- I am unable to download mails since July 22nd (today being July 25th). My MacOs is 10.4.11

- My web network works fine with web navigators: I can browse without issues withSafari and firefox

- I have turned off and on both computer and network router without positive results

- I have checked if this could be a date/hour issue: it is not

- When I check Mail's connection with assistant, it signals that both Ethernet and Wifi networks are working dandy.
- New incoming mails are on webmail server allright: they just do not download in the computer where I have the Pop account.

- I haven't changed mail settings recently.

Any of you has an idea of what might be going around?