Gmail is amazingly powerful. It can gather all your email together, whether it's webmail, POP3 mail or even other Gmail accounts, but more importantly, you can send from any email account you use through the Gmail interface.
It's also simple to set things up to access all your Gmail using your preferred desktop email client instead.
Gather your mail
Head to the Settings tab to start sorting things out. You may want to import mail, or check POP3 mail. If you're not sure which you need, start off with Importing mail - this should work for all standard webmail and many ISP-based email addresses. Under Import Mail and Contacts, click "Import mail and contacts". Sign in using your email address and password. Google will try to log you in, and if unsuccessful it will ask for your username, server and port.
This is useful for those of us who have an email address from an older ISP - such as email@example.com - but use a different pop server - such as pop3.pacific.net.au. If you need extra detail, check your webmail or ISP's configuration pages.
Once your settings are correct, you can choose whether to import one or more of your contacts, all your mail, or just new mail for the next 30 days, and whether to add a label to the email you import. Then click Start Import. It can take a couple of days for the import: Gmail will flash up a banner once it's complete. You'll have to go through the process for each email address you want imported.
If your ISP doesn't forward mail, then the Import option above will grab email that's already been sent to you, but may not fetch new mail. If you aren't getting messages, use "Check mail using POP3" instead of Import. This requires the same information to set up, but will poll your ISP at regular intervals for new mail. You can add up to 5 POP3 accounts this way.
Send from any email
Once you've added an extra email address, you can also send from it: just pick it from the drop-down menu when you compose an email. If you want to keep multiple accounts separate, head to the Accounts and Import tab in Settings and select "Reply from the same address the message was sent to". For a single email address, click "make default" for your preferred email.
You can even arrange it so that even if you send mail from one address, any replies are sent to another. Just click "edit info" next to the email address you want to modify, then click "specify a different "reply-to" address" and enter the email you want.
Gmail on desktop
If you like to download your email to a desktop email client, there's nothing to stop you doing the same with Gmail.
In the Forwarding and POP/IMAP Settings tab head to the POP download section. You can download all the Gmail you've ever received, or set the POP download to fetch only email arriving in future. Just select the appropriate box, then pick what you would like to do once your email is downloaded. You may like to keep a copy of all your mail unread on Gmail. Alternatively, you can mark the copy on Gmail read as soon as it's downloaded to your desktop client, archive it on Gmail, or even delete it from Gmail altogether. Which one of these will work best for you depends on how you use your desktop email client, and what email accounts you Import to Gmail, if any.
Once POP is enabled, head to your desktop email client, and set it up to collect your Gmail using POP. To do that, use the configuration instructions link in the POP download section in the Forwarding and POP/IMAP tab of the Gmail Settings. Gmail explains the steps in detail for most desktop email clients.
If you also enable IMAP, your Gmail account will be synchronised across any device you use to check mail.
To set up IMAP, head to the Forwarding and POP/IMAP tab in Settings. Select Enable IMAP, and then configure your email client, using the instructions Gmail provides - click the link to find details for your desktop email client or phone OS.
IMAP also means that any folders you create on your desktop email client will be replicated in Gmail, and vice versa. This can result in incredible time savings.
See the step by step screenshots: click for page 2...