This question has been asked many time before. I did search other questions. But was not able to work out.
Really sorry for repeating the same question.

I have mail and mailx and sendmail installed.

It Tried this
uuencode FILENAME.txt FILENAME.txt | mail mymail@yahoo.com

the attachment file is a text file. But i want to send it as attachment and not as a body of email.
when i get mail on yahoo.com, i get junk characters and not the actual file. also it is not sending as attachment. the junk comes as a part of email body.

I am sending mail from AIX machine..

did you check the faq?

Thank you Optimus_P for replying to my question.

I searched old questions and answers.
I tried out the commands given in those answers.

I am getting some problem in the emails. Thats why asked the same question again.
I tried to give the details of the problem that I faced.
Can you pls help me to solve this problem.

I have a plain ascii text file.
file name is FILENAME.txt
I want to send it to windows machine. The email client will be Lotus notes and yahoo.com

uuencode is using to send encoded text within a message. AFAIK mailx can't sent a standard attachment. You'll have to try metamail (metasend), mpack or mutt .

An example with metasend:

metasend -b -t someone@somewhere.org -s "Subject Here" -m text/plain -f filename