Email clients info for Linux — The Linux Kernel documentation (2023)


These days most developers use git send-email instead of regularemail clients. The man page for this is quite good. On the receivingend, maintainers use git am to apply the patches.

If you are new to git then send your first patch to yourself. Save itas raw text including all the headers. Run git am raw_email.txt andthen review the changelog with git log. When that works then sendthe patch to the appropriate mailing list(s).

General Preferences

Patches for the Linux kernel are submitted via email, preferably asinline text in the body of the email. Some maintainers acceptattachments, but then the attachments should have content-typetext/plain. However, attachments are generally frowned upon becauseit makes quoting portions of the patch more difficult in the patchreview process.

It’s also strongly recommended that you use plain text in your email body,for patches and other emails alike. may be usefulfor information on how to configure your preferred email client, as well aslisting recommended email clients should you not already have a preference.

Email clients that are used for Linux kernel patches should send thepatch text untouched. For example, they should not modify or delete tabsor spaces, even at the beginning or end of lines.

Don’t send patches with format=flowed. This can cause unexpectedand unwanted line breaks.

Don’t let your email client do automatic word wrapping for you.This can also corrupt your patch.

Email clients should not modify the character set encoding of the text.Emailed patches should be in ASCII or UTF-8 encoding only.If you configure your email client to send emails with UTF-8 encoding,you avoid some possible charset problems.

Email clients should generate and maintain “References:” or “In-Reply-To:”headers so that mail threading is not broken.

Copy-and-paste (or cut-and-paste) usually does not work for patchesbecause tabs are converted to spaces. Using xclipboard, xclip, and/orxcutsel may work, but it’s best to test this for yourself or just avoidcopy-and-paste.

Don’t use PGP/GPG signatures in mail that contains patches.This breaks many scripts that read and apply the patches.(This should be fixable.)

It’s a good idea to send a patch to yourself, save the received message,and successfully apply it with ‘patch’ before sending patches to Linuxmailing lists.

Some email client (MUA) hints

Here are some specific MUA configuration hints for editing and sendingpatches for the Linux kernel. These are not meant to be completesoftware package configuration summaries.


  • TUI = text-based user interface

  • GUI = graphical user interface

Alpine (TUI)

Config options:

In the Sending Preferences section:

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  • Do Not Send Flowed Text must be enabled

  • Strip Whitespace Before Sending must be disabled

When composing the message, the cursor should be placed where the patchshould appear, and then pressing CTRL-R let you specify the patch fileto insert into the message.

Claws Mail (GUI)

Works. Some people use this successfully for patches.

To insert a patch use Message‣Insert File (CTRL-I)or an external editor.

If the inserted patch has to be edited in the Claws composition window“Auto wrapping” inConfiguration‣Preferences‣Compose‣Wrapping should bedisabled.

Evolution (GUI)

Some people use this successfully for patches.

When composing mail select: Preformat

from Format‣Paragraph Style‣Preformatted (CTRL-7)or the toolbar

Then use:Insert‣Text File… (ALT-N x)to insert the patch.

You can also diff -Nru old.c new.c | xclip, selectPreformat, then paste with the middle button.

Kmail (GUI)

Some people use Kmail successfully for patches.

The default setting of not composing in HTML is appropriate; do notenable it.

When composing an email, under options, uncheck “word wrap”. The onlydisadvantage is any text you type in the email will not be word-wrappedso you will have to manually word wrap text before the patch. The easiestway around this is to compose your email with word wrap enabled, then saveit as a draft. Once you pull it up again from your drafts it is now hardword-wrapped and you can uncheck “word wrap” without losing the existingwrapping.

At the bottom of your email, put the commonly-used patch delimiter beforeinserting your patch: three hyphens (---).

Then from the Message menu item, selectinsert file and choose your patch.As an added bonus you can customise the message creation toolbar menuand put the insert file icon there.

Make the composer window wide enough so that no lines wrap. As ofKMail 1.13.5 (KDE 4.5.4), KMail will apply word wrapping when sendingthe email if the lines wrap in the composer window. Having word wrappingdisabled in the Options menu isn’t enough. Thus, if your patch has verylong lines, you must make the composer window very wide before sendingthe email. See:

You can safely GPG sign attachments, but inlined text is preferred forpatches so do not GPG sign them. Signing patches that have been insertedas inlined text will make them tricky to extract from their 7-bit encoding.

If you absolutely must send patches as attachments instead of inliningthem as text, right click on the attachment and select properties,and highlight Suggest automatic display to make the attachmentinlined to make it more viewable.

When saving patches that are sent as inlined text, select the email thatcontains the patch from the message list pane, right click and selectsave as. You can use the whole email unmodified as a patchif it was properly composed. Emails are saved as read-write for user only soyou will have to chmod them to make them group and world readable if you copythem elsewhere.

Lotus Notes (GUI)

Run away from it.

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IBM Verse (Web GUI)

See Lotus Notes.

Mutt (TUI)

Plenty of Linux developers use mutt, so it must work pretty well.

Mutt doesn’t come with an editor, so whatever editor you use should beused in a way that there are no automatic linebreaks. Most editors havean insert file option that inserts the contents of a fileunaltered.

To use vim with mutt:

set editor="vi"

If using xclip, type the command:

:set paste

before middle button or shift-insert or use:

:r filename

if you want to include the patch inline.(a)ttach works fine without set paste.

You can also generate patches with git format-patch and then use Muttto send them:

$ mutt -H 0001-some-bug-fix.patch

Config options:

It should work with default settings.However, it’s a good idea to set the send_charset to:

set send_charset="us-ascii:utf-8"
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Mutt is highly customizable. Here is a minimum configuration to startusing Mutt to send patches through Gmail:

# .muttrc# ================ IMAP ====================set imap_user = ''set imap_pass = 'yourpassword'set spoolfile = imaps:// folder = imaps:// record="imaps://[Gmail]/Sent Mail"set postponed="imaps://[Gmail]/Drafts"set mbox="imaps://[Gmail]/All Mail"# ================ SMTP ====================set smtp_url = "smtp://"set smtp_pass = $imap_passset ssl_force_tls = yes # Require encrypted connection# ================ Composition ====================set editor = `echo \$EDITOR`set edit_headers = yes # See the headers when editingset charset = UTF-8 # value of $LANG; also fallback for send_charset# Sender, email address, and sign-off line must matchunset use_domain # because joe@localhost is just embarrassingset realname = "YOUR NAME"set from = ""set use_from = yes

The Mutt docs have lots more information:

Pine (TUI)

Pine has had some whitespace truncation issues in the past, but theseshould all be fixed now.

Use alpine (pine’s successor) if you can.

Config options:

  • quell-flowed-text is needed for recent versions

  • the no-strip-whitespace-before-send option is needed

Sylpheed (GUI)

  • Works well for inlining text (or using attachments).

  • Allows use of an external editor.

  • Is slow on large folders.

  • Won’t do TLS SMTP auth over a non-SSL connection.

  • Has a helpful ruler bar in the compose window.

  • Adding addresses to address book doesn’t understand the display nameproperly.

Thunderbird (GUI)

Thunderbird is an Outlook clone that likes to mangle text, but there are waysto coerce it into behaving.

After doing the modifications, this includes installing the extensions,you need to restart Thunderbird.

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  • Allow use of an external editor:

    The easiest thing to do with Thunderbird and patches is to use extensionswhich open your favorite external editor.

    Here are some example extensions which are capable of doing this.

To beat some sense out of the internal editor, do this:

  • Edit your Thunderbird config settings so that it won’t use format=flowed!Go to your main window and find the button for your main dropdown menu.Main Menu‣Preferences‣General‣Config Editor…to bring up the thunderbird’s registry editor.

    • Set mailnews.send_plaintext_flowed to false

    • Set mailnews.wraplength from 72 to 0

  • Don’t write HTML messages! Go to the main windowMain Menu‣Account Settings‣youracc@server.something‣Composition & Addressing!There you can disable the option “Compose messages in HTML format”.

  • Open messages only as plain text! Go to the main windowMain Menu‣View‣Message Body As‣Plain Text!

TkRat (GUI)

Works. Use “Insert file…” or external editor.

Gmail (Web GUI)

Does not work for sending patches.

Gmail web client converts tabs to spaces automatically.

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At the same time it wraps lines every 78 chars with CRLF style line breaksalthough tab2space problem can be solved with external editor.

Another problem is that Gmail will base64-encode any message that has anon-ASCII character. That includes things like European names.


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