Environment Variables

At the time of this writing (circa version 3.8), Evolution and Evolution-Data-Server have no centralized mechanism for generating debugging output. Typically each backend module -- be it a mail backend, calendar backend, or address book backend -- uses its own environment variable to control its own debugging output. This section documents those environment variables.

Since environment variables for debugging are typically set as part of the shell command that starts a process (e.g. CAMEL_DEBUG=all evolution), it's important to know which processes run which backends.

Mail Backends

Mail backends run in the evolution application as extensions of the Camel library. The Camel library uses a single environment variable -- CAMEL_DEBUG -- to control debugging output. The general syntax of the environment variable is as follows:

CAMEL_DEBUG = "all" | module [":" subsystem] ("," module [":" subsystem])*

The special all value enables all available debugging options, but this tends to generate an overwhelming amount of output that is difficult to sift through. Enabling only the debugging options relevant to the issue at hand generally reveals the culprit more quickly.


Camel's "IMAPX" backend makes extensive use of the "subsystem" feature of Camel's debugging system. If a subsystem is not specified, as in CAMEL_DEBUG=imapx, then all subsystem options for imapx are enabled.

Available subsystem options are listed below and are shown the way they would typically be invoked.

CAMEL_DEBUG=imapx:io evolution >& logfile

The imapx:io option follows the raw IMAP protocol exchanges with the IMAP server, and is generally the most useful for debugging communication or standard-compliance issues.

Note: The remaining subsystem options are less useful than imapx:io, but are listed here for completeness.

CAMEL_DEBUG=imapx:command evolution >& logfile

The imapx:command option follows the assembling and pipelining of outgoing IMAP commands, as well as acknowledegment of untagged IMAP responses.

CAMEL_DEBUG=imapx:token evolution >& logfile

The imapx:token option follows the parsing of individual string tokens read from the network stream, and is generally only useful for debugging issues with the IMAP parser.

CAMEL_DEBUG=imapx:parse evolution >& logfile

The imapx:parse option is a higher level parsing option which indicates the expected grammar of subsequent string tokens, as defined in the IMAP RFC documents.

CAMEL_DEBUG=imapx:debug,imapx:extra evolution >& logfile

The imapx:debug and imapx:extra options seem to be for miscellaneous and narrative debugging messages. It's not clear what the distinction was meant to be for these two options.


Debugging output for Camel's POP3 backend is enabled as follows:

CAMEL_DEBUG=pop3 evolution >& logfile

This follows the raw POP3 protocol exchanges with the POP3 server, as well as miscellaneous backend processing.


Debugging output for Camel's NNTP backend is enabled as follows:

CAMEL_DEBUG=nntp evolution >& logfile

This follows the raw NNTP protocol exchanges with the NNTP server, as well as miscellaneous backend processing.


Prior to E-D-S 3.10, Camel's SMTP backend defined no debug symbol of its own and had to be enabled through the special all value.

CAMEL_DEBUG=all evolution >& logfile    # 3.8 or prior only

As of E-D-S 3.10, the SMTP backend defines its own debugging symbol:

CAMEL_DEBUG=smtp evolution >& logfile   # 3.10 or later only

This follows the raw SMTP protocol exchanges with the SMTP server.

Calendar Backends

Calendar backends run in the evolution-calendar-factory process. Each calendar backend defines its own environment variable(s) to enable debugging output, usually as a simple toggle in the form of FOO_DEBUG=1.


Debugging output for the CalDAV calendar backend is enabled as follows:

CALDAV_DEBUG={all|message:body|message:header|message|items|attachments} evolution-calendar-factory >& logfile

Multiple options can be specified as a comma-separated list.

The message* options enable libsoup's logging facilities:

The items and attachments enable additional debug output directly from the CalDAV backend.

The all option enables message:body (the most verbose of the three message* options), as well as items and attachments options.


Debugging output for the WebCal calendar backend is enabled as follows:

WEBCAL_DEBUG=1 evolution-calendar-factory >& logfile

This enables libsoup's logging facility with a log level of SOUP_LOGGER_LOG_BODY.

Address Book Backends

Address book backends run in the evolution-addressbook-factory process. Each address book backend defines its own environment variable(s) to enable debugging output, usually as a simple toggle in the form of FOO_DEBUG=1.


Debugging output for the Google address book backend is enabled as follows:

GOOGLE_BACKEND_DEBUG=1 evolution-addressbook-factory >& logfile

This seems to just output raw XML and data item counts in a few places. Does not activate any debugging facilities in GData itself.


Debugging output for the LDAP address book backend is enabled as follows:

LDAP_DEBUG=1 evolution-addressbook-factory >& logfile

This follows interactions with the LDAP server. Additionally the LDAP_OPT_DEBUG_LEVEL option is hard-coded to 4.


Debugging output for the WebDAV address book backend is enabled as follows:

WEBDAV_DEBUG={all|headers|*} evolution-addressbook-factory >& logfile

The enables libsoup's logging facilities:

Evolution Source Registry

The evolution-source-registry has muted debugging output since 3.12.9/3.13.8. It can be enabled with:

ESR_DEBUG=1 /usr/libexec/evolution-source-registry &>log.txt


You can force Evolution to be in online mode and ignore the system's connectivity status.


You can also debug the spam filtering (via SpamAssassin or Bogofilter), for example when it behaves incorrectly:

CAMEL_DEBUG=junk evolution

To enable logging of filters on console from command line (not by editing GSettings), which is available since Evolution 3.26.0, use:

CAMEL_DEBUG=filters evolution

Apps/Evolution/Debugging (last edited 2017-06-26 13:53:45 by MilanCrha)