How to Fix unable to send Email Messages in Thunderbird?

Steps to Fix Unable Send Email Messages in Thunderbird :

If you are unable to send email messages from your Thunderbird account, there can be two reasons behind this:

  • Inappropriate Thunderbird Settings
  • Blocked Port 25 by ISP (Internet Service Provider)

Solution – To resolve this error in Mozilla Thunderbird, perform the following:

Step 1: Ensure that Thunderbird settings are appropriately configured:

  • Incoming mail server (POP3/IMAP server):
  • Outgoing mail server (SMTP server):
  • Username: the full e-mail address like [email protected]
  • SMTP authentication must be enabled for the login to be successful.

Step 2: Try using alternative TCP port 2525 for SMTP Server.

Process for Backing up Thunderbird Profile

Process for Backing up Thunderbird Profile

Manually back up the Thunderbird profile

If you are comfortable with copying files and folders you can manually back up your profile. Backing up Thunderbird process can be as simple as copying a single directory to a backup location. Most of our time spends in searching where the profile folder is stored.

It’s a good idea to first get rid of any unnecessary files to reduce the size of your backup.

1. Firefox: ” Tools -> Options-> Advanced -> Network -> (under Offline Storage or Cached Web Content) -> Clear Now”

Thunderbird Clear Cache

2. Mozilla Suite/SeaMonkey: Edit -> Preferences -> Advanced -> Cache -> Clear Cache, as well as compact your mail.

seamonkey clear cache

3. Thunderbird: Compact your mail.

The simpl solution is to use Help -> Troubleshooting Information -> Show Folder to open your systems file manager at the current profile, and then copy/paste that directory somewhere safe. If your application doesn’t support that menu command see Profile_folder or Finding the profile folder on Windows to find where your profiles are stored. The profile which prefs.js file was modified most, recently is probably the profile you normally use.

A complete solution is: Backing up Thunderbird

1. Completely exit or quit the application. Mozilla Suite and SeaMonkey 1.x users on Windows should also exit Mozilla Quick Launch if it is enabled.

2. Find the “Mozilla” (for Mozilla Suite/SeaMonkey 1.x), “SeaMonkey” (for SeaMonkey 2), “Firefox”, or “Thunderbird” folder in the profile folder path that contains the registry.dat file or profiles.ini file and the “Profiles” folder (Windows and Mac) or <profile name> folder (Linux). See Profile folder – Firefox, Profile folder – Thunderbird and Profile folder – SeaMonkey for the location.

3. Copy the “Mozilla” “SeaMonkey” “Firefox” or “Thunderbird” folder to the backup location. This will back up all profiles in the default location and the “registry.dat” or “profiles.ini” file that keeps track profiles.

4. If you have created any profiles in a custom location, copy them to the backup location and make a note of the original location.

5. Mail is stored by default within the profile. If you re-configured Thunderbird, Mozilla Suite or SeaMonkey to store an accounts messages outside of the profile, you need to also copy the “local directory” for that account. Look in Account settings to find the location of each account’s local directory.

To restore a profile backup:

1. Close the application whose profile you’re going to restore. If you’re using Mozilla Suite or SeaMonkey 1.x you should also exit Mozilla Quick Launch if it’s enabled.

2. Copy each folder you backed up to the exact same location that it was in when you made the backup.

Import your Address Book in Thunderbird

How to Import your Address Book in Thunderbird?

Open Thunderbird.Open Mozilla Thunderbird

Go to Tools and Click Address Book.Thunderbird Address book

Then Click “Tools,” then click “Import” from the drop-down menu that appears. Thunderbird displays the Import window.Thunderbird personal Address book.jpg

Click the radio button next to Address Books. Click “Next.”

Click “Text file (LDIF, .tab, .csv, .txt)” from the list of available options. Click “Next.”

Browse to the location where you saved your exported Outlook contacts and double-click on the CSV file.

Click the checkbox next to “First record contains field names.”

Click the “Move Up” and “Move Down” buttons to match the Outlook contact fields to those in Thunderbird.

Click “OK” and then click “Finish.”

How to Install an Add on in Mozilla Thunderbird?

Install Add-on Extension in Mozilla ThunderBird

In an ideal world, all the add-ons you would want are officially vetted, approved, and can be found on the official website,

If you are in this category, you can simply go to the Add-ons manager tab in Thunderbird, using the toolbar entry then and enter the add-on’s name into the search box.

Installing an Add-on in Thunderbird

Once you find the add-on, click Install, then wait for it to download, then click Restart Thunderbird.

A little ideal ideal
You have given a URL for the add-on, or the add-on you want is not on the “official” page. Searched for it, as shown above, does not detect your add-on.

Go to the web page in your browser, right-click the download link with your mouse, select “Save Link in this way”, and save the XPi file to your computer that you can find again. Download is temporarily recommended that you either use your downloads folder or your desktop.

To install a downloaded XPI file into Thunderbird you have two options.


Right-click the link and select Save or Save as shown previously.

You will be invited to download and save the file. Most browsers have a default download location, often on your desktop. Say where he downloads, and what is it called. Some add-on files contain silly names like “latest -234.xpi” which is not very useful when trying to find it later

Open the add-on window in Thunderbird, there is a button on the left side of the search window.

Click this and from the subsequent menu select Install Add-on From File.

Installing an Add-on in Thunderbird

You will need to navigate in the file picker to where you saved the XPI file and select it to complete the install.


  • Open the add-ons manager ( then )
  • Drag your downloaded XPI file to the add-on manager tab and drop it.

If you are using Windows, you can even skip the desktop bit. Open your browser and Thunderbird side by side, with Thunderbird’s Add-ons tab displayed. Drag the link directly from the browser onto Thunderbird’s Add-on tab. The main advantage of this method is that you don’t need to actually save a copy of the add-on on your hard disk before it is installed.

How to Install another Language in the Dictionary on Thunderbird?

Install and Use another Language in the Dictionary on Thunderbird

If you send messages in more than one language, you can install additional spell-checking dictionaries in the Thunderbird. After installing the dictionary, switching from one language to another is easy

Language Thunderbird Add-ons are available in the form of Thunderbird Add-ons See more FAQ for more information.

Install a new language dictionary

  1. At the top of the Thunderbird window, click the Tools menu (Alt + T) and select Options, or click the Application menu button and choose Options.
  2. Select the Composition panel, followed by the Spelling tab.
  3. Click Download More Dictionaries, then click OK to close the dialog.
  4. In the opened tab, scroll through the alphabetic list of dictionaries to find the one you want.
  5. Click Download Dictionary next to the language of your choice.
  6. In the opened page of the selected dictionary, click the green Add to Thunderbirdbutton.
  7. In the Software Installation window, click Install Now.
  8. Restart Thunderbird if prompted.

That’s it! Your new dictionary is installed. To uninstall it, open the Add-ons Manager, find the dictionary on the Dictionaries or Extensions panel and click the Remove button next to it.

Switch between different languages

Select a language for one particular message

Right-click in the message you are writing and select a language in the Languages menu.Install and Use another Language in the Dictionary on Thunderbird

Set the default language for all messages

  1. At the top of the Thunderbird window, click the Tools menu (Alt + T) and select Options, or click the Application menu button and choose Options.
  2. Select the Composition panel, followed by the Spelling tab.
  3. Select the desired language from the drop-down list.
  4. Click OK to close the dialog.Install and Use another Language in the Dictionary on Thunderbird