Russ Harvey Consulting - Computer and Internet Services

Email Troubleshooting

Security | Import/Export | winmail.dat | Outlook | Mac Mail | IMAP | Gmail

Email tips and troubleshooting.

Dealing with Email Issues

If you have issues connecting with the Internet generally, you'll be unable to send or receive email. See Internet Connection Issues for troubleshooting tips.

See Computer Basics & Terminology for help with technical terms.

Email Security Issues

EFAIL | SSL/TSL Security Protocols | Email Program Vulnerabilities

Email remains one of the most important forms of communications today. It is convenient and is now available “on the go” via your smart phone.

However, you don't want to jeopardize your mail, your security or trade your privacy for ease-of-use. Don't use unsupported or obsolete software.

Understanding Encryption

I recommend that you read Encryption: Protecting Your Data on this site to understand the importance of encryption in protecting your privacy and avoiding identity theft.

EFAIL Encryption Issue

EFAIL allows someone to break email encryption under certain circumstances. At issue are email and encryption protocols in use and their aging status.

In a nutshell, EFAIL abuses active content of HTML emails, for example externally loaded images or styles, to exfiltrate plaintext through requested URLs. To create these exfiltration channels, the attacker first needs access to the encrypted emails, for example, by eavesdropping on network traffic, compromising email accounts, email servers, backup systems or client computers. The emails could even have been collected years ago. — Mozilla Thunderbird Blog

See the European EFAIL documentation includes details about the vulnerability and short-, medium- and long-term solutions.

Thunderbird, Outlook & AppleMail Vulnerable

Thunderbird, Outlook and AppleMail are vulnerable to the EFAIL encryption vulnerability if you're using S/MIME encryption or PGP encryption (through the Enigmail add-on in Thunderbird) giving the attacker access to your encrypted emails.

The Solution: Use External Encryption

The solution is to turn off internal encryption and disable HTML rendering in your email program. If you require encryption, use external encryption.

If you're worried about someone using this attack on your emails, disabling HTML rendering in your email client is a good way to mitigate risk. — Motherboard

The Cause and Potential Long-Term Solutions

Long term solutions will involve examining weaknesses in email.

SSL/TSL Security Protocols

Traditionally, email programs logged onto unsecured ports using only the user name and password for security, but later evolved to use other security measures to ensure the safe access to email on the server, particularly when sending mail.

Secure SSL/TLS Recommended

Like the Web, email started as an open system of scientists communicating with each other. Security was unnecessary and those early roots mean that today's email is not as secure as it could be.

SSL, while providing better protection than using unsecured connections, is obsolete and should not be used.

TLS replaced SSL and encrypts data such as your username and password for delivery over the Internet to maintain security and privacy. Earlier versions are not as secure and TLS 1.3 (established in 2018) or newer is recommended.

If your email program doesn't support current versions of TSL, you need to upgrade your email client or move to another email program that does.

Secure SSL/TLS settings using dedicated ports (such as IMAP on Port 993 or POP3 on Port 995) are recommended rather than Non-SSL settings on regular ports (IMAP on Port 143 or POP3 on Port 110).

Your ISP and/or email provider will have documentation on which of these protocols are available to you. Use the most secure protocol supported by the server and your email program.

Using HTTPS is strongly recommended for your webmail service, particularly where you're sharing public WiFi like in a coffee shop.

The Electronic Frontier Foundation has started STARTTLS Everywhere, a program that help improve the security of email. Check to see if your email could be secured.

Learning More

Email Program Vulnerabilities

Email programs have a number of recognized vulnerabilities which will depend upon the program and the platform (operating system) you are running it on. Those that wish to minimize spam (unsolicited junk email) should avoid software with these challenges.

Obsolete Programs Dangerous

Do NOT use obsolete email programs like Windows Live Mail, Outlook Express or Eudora.

Internet Explorer for Viewing Messages

Some Windows email programs use Internet Explorer components for displaying images and HTML (styled) messages. These programs are subject to the same vulnerabilities that Internet Explorer has.

Internet Explorer isn't the default browser on many Windows systems, especially with the arrival of Edge in Windows 10. However, by embedding an Internet Explorer zero-day and delivering it through Word, an attacker can hit targets who don't have IE set by default. [M]any applications that were once exploited in the browser can also be accessed using a Word document. — Dark Reading

Remote Images

If a remote image (one not attached to the email, but downloaded from the sender's server) is automatically displayed you risk the fact that the sender might be tracking whether the image is downloaded to your computer.

Some spammers use an identifiable image to determine which users actually open the mail in order to verify whether an email address is valid and if the message is read.

More recent email programs such as The Bat! and Thunderbird disable the downloading of images by default to protect you from this risk.

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Importing/Exporting Mail, Contacts & Settings

When changing email programs, you'll want to import the mail, contacts and settings from the old program to the new one.

Many programs will import this information from the most common current programs and even a few of the older ones.

  • Thunderbird can natively import/export address books, mail and settings in a number of formats.
  • The Bat! imports and exports email messages in .MSG, .EML and UNIX mailbox formats and now supports Exchange Web Services (EWS) protocol. See Moving to The Bat! for help moving from Pocomail.
  • Outlook see Outlook Resources for help in importing/exporting with Outlook.

Third-Party Import/Export Programs

However, many obsolete programs (like Pocomail and Barca or Outlook Express) might need an intermediary program when moving to a more recent email client.

These programs match the format of the data from program you're exporting from and convert it to the one you're importing this information into.

  • Aid4Mail MBOX Converter (free edition) converts mbox-type mailboxes to EML files.
  • Aid4Mail (from US$29.95) is an easy-to-use migration tool that can also archive mail.

Email Backup Software

You can use email backup software to both secure your important emails from loss as well as to restore it to another installation.

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Dealing with "winmail.dat" Attachments

If you receive a message with an attached file called winmail.dat you probably will be unable to open it.

Invisible to Outlook Users

The winmail.dat is invisible to users of Outlook and Outlook Express, so such users may not know what you are referring to when you mention it to them.

Other email clients, like Thunderbird, The Bat!, or webmail programs can all send enhanced HTML-based email without any problems for the recipient. This issue is specific to Microsoft's email clients.

I recommend referring them to the documentation on this page so they can view an explanation and provide solutions. The direct link is:

It's a Microsoft Format Issue

Microsoft email clients (particularly Outlook in earlier editions), use the proprietary TNEF to encode the enhanced (styled) portions of the message and sometimes attachments are encoded using TNEF.

If you have difficulty opening a messages sent by Outlook but don't see the winmail.dat attachment, it is still possible that TNEF is the issue.

TNEF provides special features which makes it useful within a network where all members are using Outlook, but this can create display issues for non-Microsoft email programs.

What Version of Outlook are You Running?

The solutions in this section vary by what version of Outlook you are using. Check Wikipedia for a history of the various versions of Outlook.

You can click on the Help menu then select About Outlook to determine what version you are using. Corporate users can contact their IT department for assistance.

It is strongly recommended that you do not use older versions of Outlook.

A Plain-Text-Only Solution

The easiest solution depends upon the person re-sending the message as a plain-text message. Any other formatting (including Rich Text Format, enhanced (HTML) or messages composed in MS Word) will create this problem for non-Outlook users unless you disable TNEF.

Disabling TNEF

In the following section you need to know what version of Outlook you're using because Microsoft changed its approach in Office 2003 (XP) and again with Office 2007.

For Microsoft Office Outlook 2007 or later follow these steps to turn off TNEF:

  1. On the Tools menu, click Options, click the Mail Format tab.
  2. In the Compose in this message format list, click Plain Text or HTML, and then click OK.

The following similar responses to questions about winmail.dat and more modern version of Office are found in the Microsoft Community:

For Microsoft Office Outlook before 2007 follow these steps to turn off TNEF:

  1. On the Tools menu, click Options, click the Mail Format tab.
  2. In the set the Send Format to either Plain Text or HTML. Do not select Rich Text format and be sure that you uncheck the "Use Microsoft Word to Edit Email Messages" box, then click OK.

Users of earlier versions of Outlook (97/2000) should simply send the message as plain text as any other formatting (including Rich Text or HTML format as well as messages composed in MS Word) will create this problem for non-Outlook users.

Microsoft provides a more technical solution based upon external domains for Microsoft Exchange 2007 users that may help your IT department determine a solution for all addresses external to your network. Note that Microsoft Exchange Server 2007 is no longer supported.

It is strongly recommended that you do not use older versions of Outlook — upgrade to a currently-supported version or move to a recommended email client.

Disable MS Word as Email Editor in Outlook XP or 2003

Unless you are exclusively sending messages within an internal department, Outlook 2002 (XP) and 2003 users will want to disable Microsoft Word as your default email editor because anyone not using Outlook or Outlook Express may be unable to read your message (or not as you intended).

To disable Microsoft Word as your default email editor in Microsoft Outlook:

  1. On the Tools menu, click Options.
  2. Click on the Mail Format tab and uncheck the "Use Microsoft Word to edit email messages" box, then click OK.

Microsoft Documentation

Other Explanations

Third Party Solutions

  • Eolsoft's Winmail Opener (also available on allows you to view and extract contents of TNEF messages. Free.
  • WMDecode for Windows is a time-limited free utility to recover the information in winmail.dat files. You can re-download the file again later, or purchase the program for US$10.
  • TNEF's Enough is a solution for Mac OS 9 and X users.

Why it Matters

As you can imagine, most people will simply ignore your message or fret over their inability to view the winmail.dat attachment. Take a look at the suggestions in the Email Newsletters section for some ideas if you are sending out regular updates of any kind to a variety of people.

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Outlook Resources

If you decide to move to Outlook, be aware that I neither use nor recommend Outlook and therefore cannot provide the level of support I can with my recommended email programs. You'll need to find alternative support.

You need to be aware of the winmail.dat issue that affects users of many non-Microsoft email program users because it is invisible to you but can affect many of those you send emails to unless you're restricted to an office environment entirely composed of Outlook users.

I've provided the following external resources to help you learn more about using Outlook and dealing with its issues.

Using Outlook

Backing Up Outlook

Troubleshooting Outlook

Outlook Utilities

  • The OutlookAddressBookView displays the details of all recipients stored in the address books of Microsoft Outlook.
  • Aid4Mail (from US$19.95) can migrate, archive and analyze the messages in all your email programs. It does this without modifying the original messages.

Moving To/From Outlook

You may need to use a third-party import/export solution.

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Dealing with Mac Mail Issues

Apple MacIntosh users face similar issues than Windows users. These resources may help you to resolve them:

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IMAP Issues

Traditionally, people had only a single computer and downloaded all message to that one computer, storing important messages forever using POP/SMTP settings.

However things have changed.

We Want Anywhere Access

Today people want copies of their messages on their computer, laptop, smartphone and tablet.

Most ISPs (e.g. Shaw, Telus, Gmail, etc.) simply give people what they ask for, without explaining the issues or potential problems.

So they tell their customers to set up their email using IMAP usually without any current reference to POP/SMTP settings.


IMAP, POP and SMTP are email protocols and important only when configuring email retrieval.

Once setup, email will be managed transparently if the settings are correct.

IMAP then mirrors the messages on the server AND on all IMAP-connected devices.

That means you have simultaneous access to your email on multiple computers and other devices — including sent messages.

Sounds perfect, doesn't it? But there are potential downsides if you're not careful.

The IMAP Downside

You need to understand how IMAP works and what is different from traditional POP/SMTP email protocols to understand what you're trading for that any time/everywhere access to all your mail.

IMAP Not Great for Archiving

Email clients using POP/SMTP downloaded email messages from the server and retained them indefinitely on our computers unless we manually delete them. This included copies of sent messages (but only on that one computer).

With IMAP, when you delete a message it deletes in on that device, the server and all other IMAP-connected devices.

So, you need to leave ALL your messages on the server, rather than deleting them from the server when they've successfully downloaded to your computer.

  • Most email accounts have limits on how much you can store on their servers.
  • Once you pass that limit the ISP may simply delete the oldest messages OR “bounce” all new incoming messages (often arbitrarily and without warning).
  • You can purchase extras storage, but some ISPs limit the amount of space you can purchase even though their costs to provide storage has greatly decreased.

Essentially, IMAP means that you could potentially lose important emails by deleting them on one of your devices, running out of server space or simple user errors.

Primary Account POP/SMTP

One possible solution is to use a POP/SMTP primary account with other devices using IMAP when you're away from your computer. If you only use your phone for mail, this issue won't work.

Set up and use a primary account (using POP/SMTP) so that you can retain your important email on your main computer — archiving important messages over the long term.

That primary account should NOT be an IMAP account.

Of course, you'll need to create regular backups of the mail on that computer in case of computer failures or viruses.

IMAP for Secondary Accounts Only

Use IMAP only on a secondary email account for messages on all your portable devices (e.g. smartphones, tablets, secondary laptops).

You can still access the mail on your primary account on your remote devices provided this account is configured for POP/SMTP. You'll be able to access NEW message as long as the primary computer has not accessed them.

If you need more, you can change the settings on your primary computer to leave mail on the server for 10 days (or another setting that works for you). That way the primary computer controls what is left on the server and for how long.

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Gmail Issues

Subscription Lists Broken

Gmail made changes that broke how subscription lists were dealt with. This created problems for people subscribed to lists.

What Happened?

Gmail changed how email subscriptions were sorted. The Primary category was designed so you could quickly find your most important emails easier.

Mail deemed less-important was moved into either the Social (Facebook notifications, etc.) or Promotions (bulk mail such as ads but also subscriptions, updates and more) categories.

Unfortunately, subscription lists and update notices were categorized as Promotions, along with “junk” ads.

How to Fix It

  1. Click on the Promotions tab and select messages you wish to go into your primary mailbox.
  2. Drag the selected message onto the Primary tab.
  3. A pop-up message will ask if you wish to do this for all future messages from the addressee of the dragged message. Say “Yes.”
  4. Continue to monitor the Promotions inbox to ensure that other messages aren't getting left behind.

Alternatively, you can turn off the new tabs completely by going to the settings, click on the Inbox tab and deselect the tabs you don't want to use (e.g. Promotions) then save the changes.

Related Resources

Related resources on this site:

or check the resources index.

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Updated: October 17, 2019