We recently switched from Windows 7 to Ubuntu 16. Everything is going well. But I am confusing how can I transfer my POP3 mails from Microsoft Outlook 2007 (PST file) to Thunderbird in Ubuntu with actual format. Is there any easier way without any software purchase? Any suggestions would be appreciated. Thanks in advance.

Put
import pst to thunderbird
In your favorite search engine...

Thank you

...and why didn't you load the LATEST Ubuntu 18.xx??
We'll suggest (again) that you read the "Question Guidelines", and perform basic research first before posting a question.

Because the user is comfortable with 16.04

What I have tried:

1> Ref link: https://www.techwalla.com/articles/h...in-thunderbird
I tired from Step2 as I cannot install Outlook in Ubuntu. Its successfully imported but the few email's format are getting changed. Please find the attached screenshot.

2> Through Thunderbird ImportExport Tools, but the result is same as above.

Attached Thumbnails

 

So if this is your 'user'/client, you are doing them a disservice. Keeping them on an older version just keeps whatever bugs/problems that version had there, while keeping all the improvements away. And this means in far less time their system will go EOL, and it will be a HUGE jump to go to version 20/whatever is out at that time, versus even having the ability to do an in-place upgrade.
And we have NO IDEA what you've done/tried unless you tell us. You didn't post this initially, nor tell us what you already tried....or did you try these things after you were told to look???

Think about what you're seeing; you're seeing the result of going from Windows to Linux. Export the mail in Outlook to a different format, rather than trying to import the .PST file. Or run Thunderbird on a Windows system, import mail THERE, and then you can go from Thunderbird-to-Thunderbird, with no issues.

Yes, I tried these before posting here. And I am sorry that I haven't mentioned in my initial thread.

I have also to import from Windows system using Thunderbird. In this case all mails are successfull imported from Outlook but few mail's format are getting changed. Please check the attached screenshot of my previous post.

Not sure what you're saying. Again:

• Install Thunderbird on Windows...import the .PST file there.
• Export Thunderbird file(s) to Linux
• Import into Thunderbird there.

AGAIN: your formatting issues are due to going from Windows to Linux, and from a proprietary email system to an open one. You may actually have to do some work to get this done, in that a script for strip out such things could be written.

Your screenshot appears to be an html email source view.
What is that a screenshot of? In which application?

@TBOne, Yes, I followed the steps that you mention.

@scasey, said screenshot is from Thunderbird after imported Outlook to Thunderbird in windows

...and do they have Thunderbird set to view HTML emails, or plain text????

Yes, HTML view is already enabled in Thunderbird as maximum HTML emails are showing perfectly.

No idea what a "maximum HTML email" is. AGAIN: Outlook is not an open standard; it is known to do such things with formatting, so if you want your emails 'formatted' somehow, you will (AGAIN) need to write a script to perform this operation.

Find it hard to believe that you'll get HTML code in one email, but have plain text in another.