Sending mail - problem with authentication

[kremuwa]

Hello. I wanted to add an option to my application, which lets user to send e-mail to my mailbox (my mail adress is set in the source code). I found the source code for this feature on the net and everything is quite good until... the SMTP server is sending me responses like: "Server XYZ requires Authentication .... blah blah". As SMTP server I'm using popular mail services' servers and they obviously requires Authentication. What does it mean? How to do the Authentication? I tried to look for servers withoud this need but the results were terrible - I haven't found anything. I can't use localhost, because it won't work for other users (who don't have servers installed).

Help me, please . Thanks in advance.