Follow the steps detailed below to use Mozilla
Thunderbird to send/receive emails.
1. Start Mozilla Thunderbird. On the File menu,
click New -> Account.

2. In the Account Wizard dialog box, select
Email account and then click Next.

3. In the Your Name box, type the name that you
want others to see when you send a message, and your complete email address of
the type user@yourdomainname.com in
the Email Address field and then click Next.

4. In this dialog box, select the type of
incoming server (POP or IMAP) as per
your choice. Incase you choose POP, you need to enable the Use Global Inbox
checkbox as shown below.

If you choose IMAP, the Use Global Inbox
checkbox will automatically disappear.

5. Enter the Incoming Server as pop.yourdomainname.com if you
selected POP in the above step and imap.yourdomainname.com if you selected IMAP.
The Outgoing Server address in any case will be
entered as smtp.yourdomainname.com. Once this is done, click Next.

6. In the Incoming User Name field,
enter your complete email address of the type user@yourdomainname.com.

7. In the Account Name field, you can enter any
name via which you would like to refer this mailbox (Sales, Support, etc.) Once this
is entered, click Next.

8. The Congratulations! dialog box should
appear next. You can select the Download messages now checkbox and click
Finish.

Your messages will start downloading and will be visible in Local
Folders under Inbox by default.

IMPORTANT
Usually, the port used for the Outgoing Mail
Server/SMTP Service is 25. However, there might be a situation where your ISP
might be blocking the use of port 25 for SMTP service. Many ISPs block port 25
in order to minimize the amount of spam sent using their network. If you are
facing issues sending mails using the default port 25, you can confirm with
your ISP whether port 25 is indeed blocked by them.
To circumvent this, ResellerClub
allows you to use an alternate port 2525 for sending mails if
port 25 is blocked -
a. In Mozilla Thunderbird, on the Tools menu,
click Account Settings.

b. Click on Outgoing Server (SMTP).
In the Outgoing Server (SMTP)
Settings section as seen in the below image, select entry for your
domain name and click Edit.
c. Replace the default port number
25 with the alternate port number 2525.
d. Click OK in the SMTP Server
and Account Settings windows to save the changes.