| Horde_Smtp_Password | Interface to allow dynamic generation of SMTP password. |
| Horde_Smtp | An interface to an SMTP server (RFC 5321). |
| Horde_Smtp_Connection | PHP stream connection to a SMTP server. |
| Horde_Smtp_Debug | Handles debugging output for a Horde_Smtp object. |
| Horde_Smtp_Exception | Exception handler for the Horde_Smtp package. |
| Horde_Smtp_Exception_Recipients | Extended exception class that provides information on recipient addresess that failed. |
| Horde_Smtp_Filter_Body | Stream filter to determine whether body needs to be sent as 8-bit (STD 71/RFC 6152) or binary (RFC 3030). |
| Horde_Smtp_Filter_Data | Stream filter to escape output to the SMTP DATA command (RFC 5321 [4.1.1.4]). |
| Horde_Smtp_Lmtp | An interface to an LMTP server (RFC 2033). |
| Horde_Smtp_Password_Xoauth2 | Generates an OAuth 2.0 authentication token as used in the Gmail XOAUTH2 authentication mechanism. |
| Horde_Smtp_Translation | Translation wrapper class for Horde_Smtp. |