Here's some basics about using multiple email accounts.
First, there really is no limit how many email accounts you can have. Normally each account consists of one email address, but some email providers allow you to use so called aliases when in fact you can have more email addresses belonging to one email account. However, to keep this simple let's just stay in basics; one email account = one email address.
You can use different email accounts for different purposes. All accounts can be from the same provider, or all accounts can have a different provider. You can decide to whom you want to give which address, for instance only to give your private email address to family and friends, and work email address only to co-workers, customers and so on.
A quite typical scenario is to have three accounts: one for work, one for personal, private mail and one to use when you need to provide an email address to for instance login in to a website but you would not like to provide your real email address. You could for instance have these three email accounts from three different providers: a work email address
workmail@gmail.com, an email for private mail
privatemail@live.com and one to use when you do not want to use the "real" email addresses
spammail@yahoo.com. (Please notice, these three are only for demonstration purposes. They are not real email addresses.)
When you now send an email from any of these three accounts, and the receiver replies it, the reply is by default sent to the same address as from which the mail was sent. However, you can in most cases change this so called
Reply-To email address, so that for instance when you send an email from
workmail@gmail.com to me and I reply to it, you get my reply to
privatemail@live.com instead of the
workmail@gmail.com.
Usually every web based email provider has the option to change the
Reply-To address. Here's for instance how to change it in
Hotmail (@hotmail.com, @live.com and @msn.com addresses):
- In Live (Hotmail), click Options > More Options under your name on top right corner of the page:
.

. - Click Reply-To address under Writing email:
.

- Select Other address and add any valid email address where you want to receive replies. Click Save:
.

Done. Now the replies to your email are no longer sent to your original email address. Instead, they are sent to this secondary Reply-To address.
If you use an email client application to manage your email, this can be done from your email client application's settings. Here's how to change Reply-To address in
Windows Live Mail 2011:
- Open the main menu by clicking the white down arrow on top left corner. Select Options > Email accounts:
.

. - Select the account you want to modify, click Properties:
.

. - Under General tab, add the Reply-To address and click OK:
.

And one more, here's the same done in
Outlook 2010:
- Click File > Info > Account Settings > Account Settings:
.

. - Under E-mail tab, select the account you want to modify, click Change:
.

. - Click More Settings:
.

. - Under General tab, add the Reply-To address you want to. Click OK:
.

So, to use multiple email accounts is easy and has no limits, as far as you can remember all your addresses and passwords
You can decide if you want to use different accounts when sending email and get replies back to respective accounts, or if you want to gather all replies to one account using a global Reply-To address.
Kari