<div>
<div class="content wysiwyg-content">
An error occurred while sending mail. The mail server responded: &nbsp;4.7.1 &lt;unknown[193.203.81.165]&gt;:<wbr /> Client host rejected: Access denied. Please check the message recipient pattokee@hotmail.com and try again.
</div>
</div>


An error occurred while sending mail. The mail server responded:  4.7.1 <unknown[193.203.81.165]>: Client host rejected: Access denied. Please check the message recipient pattokee@hotmail.com and try again.

Mozilla Thunderbird

An email client, email reader or more formally mail user agent (MUA) is a computer program in the category of groupware environments used to access and manage a user's email. A web application that provides message management, composition, and reception functions may internally act as an email client; as a whole, it is commonly referred to as webmail. Likewise, email client may be referred to a piece of computer hardware or software whose primary or most visible role is to work as an email client. Email clients can also have other systems, like calendars, notes and contact managers.

Email Clients

Thunderbird is an email, newsgroup, news feed, and chat (XMPP, IRC, Twitter) client that supports POP and IMAP and LDAP address completion. The vanilla version is not a personal information manager, although the Mozilla Lightning extension adds PIM functionality. Thunderbird can manage multiple email, newsgroup, and news feed accounts and supports multiple identities within accounts. Features such as quick search, saved search folders, advanced message filtering, message grouping, and labels help manage and find messages. Thunderbird incorporates a Bayesian spam filter, a whitelist based on the included address book, and can also understand classifications by server-based filters such as SpamAssassin. Extensions allow the addition of features.