Email messages including Hebrew characters are generally encoded in Unicode (UTF-8), ISO-8859-8-I ("Logical Hebrew") or Windows-1255 ("Windows Hebrew"). Thunderbird, a free open source mailer with freely available spell checking dictionaries in multiple languages including Hebrew, and Outlook Express / Windows Mail, preinstalled in Windows, are two of the major mailers that support the three encodings and the bidirectional algorithm. Other mailers for Windows that support Hebrew script include SeaMonkey, Opera, i.Scribe, InScribe and Outlook.
For the sake of crossplatform compatibility it is recommended to avoid using Windows-1255 and use either Unicode (UTF-8) or ISO-8859-8-I for messages containing Hebrew characters. If you have to mix Hebrew vowel signs and non-ASCII characters as well, you have to choose Unicode (UTF-8). The availability of fonts for Hebrew characters and the support of Unicode (UTF-8) and the bidirectional algorithm are not universal, so before you send a message in Hebrew characters, make sure that your recipient has Hebrew fonts and uses a Unicode-compliant mailer.
BiDi Mail UI enables you to right-align plain text messages you read and compose with Thunderbird. Outlook Express / Windows Mail enables you to right-align paragraphs only if you use HTML format. If you use Outlook Express to compose a message in Hebrew characters in plain text format, you cannot right-align paragraphs; they will be left-aligned. Although Hebrew characters are displayed from right to left, punctuation marks are considered neither left-to-right nor right-to-left and change their directionality based on contexts.
For various reasons, however, it is generally considered part of good email netiquette to avoid HTML mail and send messages in plain text format except when sending to people who have given you prior consent. In order to make plain text as the default format of outgoing messages in Thunderbird, 1) go from the toolbar to "Tools" -> "Account Settings", 2) select an account you want to apply this setting to, 3) open "Composition & Addressing", and 4) uncheck "Compose messages in HTML format". To do the same in Outlook Express / Windows Mail, 1) go from the toolbar to "Tools" -> "Options" -> "Send", and 2) check "Plain Text" for "Mail Sending Format".
It is recommended to disable the option of receiving messages in HTML format to protect your security and privacy. It is possible to embed in HTML messages not only malicious scripts that may harm your computer but also the so-called web bugs, which are tiny images abused by spammers to ensure that your email address is valid and to send you more spam messages. To disable the receipt of HTML mail in Outlook Express / Windows Mail, 1) go from the toolbar to "Tools" -> "Options" -> "Read", and 2) check "Read all messages in plain text". To disable it in Thunderbird, 1) type "about:config" (without quotes) on the address bar, 2) find the line "mailnews.display.prefer_plaintext" and doubleclick it, and 3) change the value from "false" to "true". This way all your incoming messages in HTML format will be converted automatically to plain text format.