General Information

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What is Sylpheed-Claws?

Sylpheed-Claws is an e-mail client (& news reader) based on GTK+, running on the X Window System, and aiming for

  • Quick response
  • Graceful, and sophisticated interface
  • Easy configuration, intuitive operation
  • Abundant features

Sylpheed-Claws is the extended version of Sylpheed.

What are the differences between Sylpheed-Claws and Sylpheed?

There are many differences.

For an incomplete list of features, and differences between Sylpheed-Claws and Sylpheed, see

Where can I get Sylpheed-Claws?

See the Downloads page

Who writes Sylpheed-Claws?

Sylpheed-Claws is developed by the Sylpheed-Claws Team.

What does the 'Sylpheed' mean?

It means 'light weight', like air. This comes from the name of the wind spirits, the Sylphs.

How does Sylpheed-Claws store mails?

Mails are stored in the MH mailfile format as used by MH and EMH. Maildir and mbox format are supported via two plugins available on the Plugins page.

Does Sylpheed-Claws have mail filtering?

Yes. You can find it in Configuration->Filtering... tab.

Can Sylpheed-Claws handle local unix mailboxes?


Can Sylpheed-Claws handle IPv6?

Yes, IPv6 is fully supported in Sylpheed-Claws.

How many POP3, News or IMAP accounts can I set up in Sylpheed-Claws?

The number is unlimited. The limit is reached when your computer stops responding.

Does Sylpheed-Claws support encryption like GPG?

Yes. GPG is implemented and works fine. For activating it in Sylpheed-Claws, see the Installation_and_Configuration#How_do_I_enable_GPG_support_in_Sylpheed-Claws.3F section.

How does Sylpheed-Claws check for MIME types?

Sylpheed-Claws uses the Mutt type of mime checking.

Does Sylpheed-Claws allow me to write HTML styled messages?

No. A discussion has gone around over this topic, and the outcome was that HTML mail is not wanted. If you really need to send HTML, you can of course attach a webpage to an e-mail. Several patches have been made to facilitate better HTML handling in Sylpheed. You can find these patches at the Sylpheed Patch Page (see further down in the document).

Does Sylpheed-Claws have name completion in the address fields?

Yes. When you search for a name that starts with "don", type "don" (without the quotes) and press the TAB key. This will show you the correct name (when only one "don" exists in your addressbook. Otherwise a dropdown list appears, which allows you to select the name you want. E.g. Donald Duck, Don Johnson. But also e-mail addresses starting with "don" will appear in the list (like "").

Why is Sylpheed-Claws so fast?

That's what it is designed for!

How can I send in patches, report bugs, talk about Sylpheed-Claws with others?

To talk to others, you should join the Sylpheed-Claws users' mailing list at

Can I import a mbox into Sylpheed-Claws' MH mailfolders?

Yes, just create/select the folder you want your mails in, and select "Import mbox file" in the File menu.

Can I use procmail to sort my mails with the MH mail handling?

Yes. Just make sure that you add /. to the end of a rule so procmail knows that you are filtering into an MH mail folder. Example :


* ^Subject:.*sylpheed


Check man procmail for details.

When I upgrade Sylpheed-Claws, are there things I should be aware of?

Yes, some more critical than others.

You should always read the RELEASE_NOTES document that is included in the release tarballs. The release notes can also be viewed on the Sylpheed-Claws Source Forge site Files page listing by clicking the version number of the release.

How can I quickly update the views in Sylpheed-Claws?

Just press Alt-U or select "update" from the summary menu.

Why does Sylpheed-Claws allow me to open more than one instance at the same time for the same user on a network?

Sylpheed-Claws opens a Unix-domain socket using a name constucted from your TMPDIR path plus your UID. This socket is used to arbitrate multiple instances on a given machine. In Linux, at least, named Unix-domain sockets are known only locally, to the creating machine. Pointing your TMPDIR environment variable to /home/yours/tmp doesn't have the desired effect, as the socket definition would need to be propagated across the LAN and isn't.

Does Sylpheed-Claws have an anti-spam feature?

Yes. It has a Spam Assassin plugin. You can find details of it on the Plugins FAQ Page.

You can also use other spam filters via Actions, such as Bogofilter. Instructions on how use Bogofilter with Sylpheed-Claws can be found on the Bogofilter FAQ.

More information about using Bogofilter or Popfile can be found on the Using Sylpheed Claws with other programs page.

Does Sylpheed-Claws support Return Receipts?


To request a Return Receipt use '/Options/Request Return Receipt' in the Compose window.

When you receive a message that requests a Return Receipt a notification area is shown just above the message view. You can either use the 'Send receipt' button, or ignore the request - no receipts are sent automatically.

Why is Sylpheed-Claws slow to load big folders?

Certain options, although handy, slow down Sylpheed-Claws:

- Use addressbook to display sender
- Thread using subject in addition to standard headers
- (GPG) Automatically check signatures
- Sort by Subject, From or To instead of Date or other non-string headers
- Processing rules, especially those based on "Whole message" or "Body" contains ...