General question about mail(), phpmailer and PEAR:mail

[jeddi]

I am a bit confused about mail(), phpmailer and PEAR:mail

I am building my subscriber list which is held in the
mySQL database "client" table and I want to start sending them a newsletter.

My list will probably get up to around 20,000

I would like know if emails are getting through or if they are being rejected, so I can keep the subscriber list clean.

It would br great to be able to send out HTML email but with an alternative text email for those that don't except HTML.

Now, I was just going to use php mail() command
from within my own script which simple loops through the client
table, but I read this at php.net:

Note: It is worth noting that the mail() function is not suitable for larger volumes of email in a loop. This function opens and closes an SMTP socket for each email, which is not very efficient.
For the sending of large amounts of email, see the » PEAR::Mail, and » PEAR::Mail_Queue packages.

It has also been suggested that I use phpMailer or SwiftMail.

Now,
I have to admit I am a bit confused though.

Having read a few tutorials about all this

There is phpMailer
and there is SwiftMail
and there is PEAR:Mail

Are these three just similar methods of doing the same thing ?
i.e. they are all OOP classes that in the end use the
php mail() command ?


Then there is Sendmail.

I think sendmail is a server program like postfix - is that right ?

And does the mail() command send the email out using the server program ( sendmail or postfix ) ?

I have downloaded phpMailer and about to install it but,
to be honest I am not sure is setting up phpMailer is the way to go
, would PEAR be better ( or even Swift) ?

Can't use both I guess if they do the same thing !!

Would very much appreciate it if someone could explain the relationship of all these "bits" of the puzzle.

Thanks