There are only a few free email account providers which are worth to mention. We have selected only these and compiled in this brief comparison:
Gmail is a well known brand from Google. Estimated in 2004, it has reached 350 million worldwide users which makes Gmail one of the most popular free email service in the world. It's available in 54 languages. Gmail features 10GB of free space which you can use for whatever you like. This is important, because many other providers provide a lot of space which can be used solely for emails (not media files). Gmail offers one of the best spam filters available in the industry, so don't have to worry about these pharmacy ads you may receive in bulk. You can access your Gmail account using whatever email client you like, because they provide IMAP/POP3.
It's the third biggest free email account provider. In 2011 they've had 300 million of users. It's a much older service than Gmail, since it was launched in 1997. Their accounts feature unlimited storage and attachments up to 100MB, POP3 and IMAP access. You should remember that if you don't access your account at least one each 4 months, it will expire and you will lost all your emails. Yahoo! Mail has also a great spam filter which elimiates a huge percentage of unwated messages.
Operated by Microsoft with almost 370 million of active users. Hotmail was launched in 1996 and in 1997 it was acquired by Microsoft. They offer their service in 36 languages. Their free version features 5GB of storage and attachments up to 25MB. Unlike the previous two sevices they do not provide IMAP access(while POP3 is available).