| Horde_Mail_Exception | Exception handler for the Horde_Mail class. |
| Horde_Mail_Mbox_Parse | This object allows easy access to parsing mbox data (RFC 4155). |
| Horde_Mail_Rfc822 | RFC 822/2822/3490/5322 Email parser/validator. |
| Horde_Mail_Rfc822_Address | Object representation of a RFC 822 e-mail address. |
| Horde_Mail_Rfc822_Group | Object representation of a RFC 822 group e-mail address. |
| Horde_Mail_Rfc822_GroupList | Container object for a collection of group addresses. |
| Horde_Mail_Rfc822_Identification | Class to parse identification headers (RFC 5322 [3.6.4]): Message-ID, References, and In-Reply-To. |
| Horde_Mail_Rfc822_List | Container object for a collection of RFC 822 elements. |
| Horde_Mail_Rfc822_Object | Object representation of an RFC 822 element. |
| Horde_Mail_Translation | Translation wrapper for the Horde_Mail package. |
| Horde_Mail_Transport | Mail transport base class. |
| Horde_Mail_Transport_Lmtphorde | LMTP implementation using the Horde_Smtp package. |
| Horde_Mail_Transport_Mail | Internal PHP-mail() interface. |
| Horde_Mail_Transport_Mock | Mock implementation, for testing. |
| Horde_Mail_Transport_Null | Null implementation of the mail transport interface. |
| Horde_Mail_Transport_Sendmail | Sendmail interface. |
| Horde_Mail_Transport_Smtp | SMTP implementation. |
| Horde_Mail_Transport_Smtphorde | SMTP implementation using Horde_Smtp. |
| Horde_Mail_Transport_Smtpmx | SMTP MX implementation. |