Email clients info for Linux¶
These days most developers use
git send-email instead of regular
email clients. The man page for this is quite good. On the receiving
end, maintainers use
git am to apply the patches.
If you are new to
git then send your first patch to yourself. Save it
as raw text including all the headers. Run
git am raw_email.txt and
then review the changelog with
git log. When that works then send
the patch to the appropriate mailing list(s).
Patches for the Linux kernel are submitted via email, preferably as
inline text in the body of the email. Some maintainers accept
attachments, but then the attachments should have content-type
text/plain. However, attachments are generally frowned upon because
it makes quoting portions of the patch more difficult in the patch
It’s also strongly recommended that you use plain text in your email body, for patches and other emails alike. https://useplaintext.email may be useful for information on how to configure your preferred email client, as well as listing recommended email clients should you not already have a preference.
Email clients that are used for Linux kernel patches should send the patch text untouched. For example, they should not modify or delete tabs or spaces, even at the beginning or end of lines.
Don’t send patches with
format=flowed. This can cause unexpected
and 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 patches because tabs are converted to spaces. Using xclipboard, xclip, and/or xcutsel may work, but it’s best to test this for yourself or just avoid copy-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 Linux mailing lists.
Some email client (MUA) hints¶
Here are some specific MUA configuration hints for editing and sending patches for the Linux kernel. These are not meant to be complete software package configuration summaries.
TUI = text-based user interface
GUI = graphical user interface
When composing the message, the cursor should be placed where the patch should appear, and then pressing CTRL-R let you specify the patch file to insert into the message.
Claws Mail (GUI)¶
Works. Some people use this successfully for patches.
To insert a patch use(CTRL-I) or an external editor.
If the inserted patch has to be edited in the Claws composition window “Auto wrapping” inshould be disabled.
Some people use this successfully for patches.
- When composing mail select: Preformat
from(CTRL-7) or the toolbar
Then use:(ALT-N x) to insert the patch.
You can also
diff -Nru old.c new.c | xclip, select
, then paste with the middle button.
Some people use Kmail successfully for patches.
The default setting of not composing in HTML is appropriate; do not enable it.
When composing an email, under options, uncheck “word wrap”. The only disadvantage is any text you type in the email will not be word-wrapped so you will have to manually word wrap text before the patch. The easiest way around this is to compose your email with word wrap enabled, then save it as a draft. Once you pull it up again from your drafts it is now hard word-wrapped and you can uncheck “word wrap” without losing the existing wrapping.
At the bottom of your email, put the commonly-used patch delimiter before
inserting your patch: three hyphens (
Then from themenu item, select and choose your patch. As an added bonus you can customise the message creation toolbar menu and put the icon there.
Make the composer window wide enough so that no lines wrap. As of KMail 1.13.5 (KDE 4.5.4), KMail will apply word wrapping when sending the email if the lines wrap in the composer window. Having word wrapping disabled in the Options menu isn’t enough. Thus, if your patch has very long lines, you must make the composer window very wide before sending the email. See: https://bugs.kde.org/show_bug.cgi?id=174034
You can safely GPG sign attachments, but inlined text is preferred for patches so do not GPG sign them. Signing patches that have been inserted as inlined text will make them tricky to extract from their 7-bit encoding.
If you absolutely must send patches as attachments instead of inlining them as text, right click on the attachment and select, and highlight to make the attachment inlined to make it more viewable.
When saving patches that are sent as inlined text, select the email that contains the patch from the message list pane, right click and select. You can use the whole email unmodified as a patch if it was properly composed. Emails are saved as read-write for user only so you will have to chmod them to make them group and world readable if you copy them elsewhere.
Lotus Notes (GUI)¶
Run away from it.
IBM Verse (Web GUI)¶
See Lotus Notes.
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 be used in a way that there are no automatic linebreaks. Most editors have anoption that inserts the contents of a file unaltered.
vim with mutt:
If using xclip, type the command:
before middle button or shift-insert or use:
if you want to include the patch inline.
(a)ttach works fine without
You can also generate patches with
git format-patch and then use Mutt
to send them:
$ mutt -H 0001-some-bug-fix.patch
It should work with default settings.
However, it’s a good idea to set the
Mutt is highly customizable. Here is a minimum configuration to start using Mutt to send patches through Gmail:
# .muttrc # ================ IMAP ==================== set imap_user = 'email@example.com' set imap_pass = 'yourpassword' set spoolfile = imaps://imap.gmail.com/INBOX set folder = imaps://imap.gmail.com/ set record="imaps://imap.gmail.com/[Gmail]/Sent Mail" set postponed="imaps://imap.gmail.com/[Gmail]/Drafts" set mbox="imaps://imap.gmail.com/[Gmail]/All Mail" # ================ SMTP ==================== set smtp_url = "smtp://firstname.lastname@example.org:587/" set smtp_pass = $imap_pass set ssl_force_tls = yes # Require encrypted connection # ================ Composition ==================== set editor = `echo \$EDITOR` set edit_headers = yes # See the headers when editing set charset = UTF-8 # value of $LANG; also fallback for send_charset # Sender, email address, and sign-off line must match unset use_domain # because joe@localhost is just embarrassing set realname = "YOUR NAME" set from = "email@example.com" set use_from = yes
The Mutt docs have lots more information:
Pine has had some whitespace truncation issues in the past, but these should all be fixed now.
Use alpine (pine’s successor) if you can.
quell-flowed-textis needed for recent versions
no-strip-whitespace-before-sendoption is needed
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 name properly.
Thunderbird is an Outlook clone that likes to mangle text, but there are ways to coerce it into behaving.
After doing the modifications, this includes installing the extensions, you need to restart Thunderbird.
Allow use of an external editor:
The easiest thing to do with Thunderbird and patches is to use extensions which open your favorite external editor.
Here are some example extensions which are capable of doing this.
“External Editor Revived”
It requires installing a “native messaging host”. Please read the wiki which can be found here: https://github.com/Frederick888/external-editor-revived/wiki
To do this, download and install the extension, then open thewindow, add a button for it using then just click on the new button when you wish to use the external editor.
Please note that “External Editor” requires that your editor must not fork, or in other words, the editor must not return before closing. You may have to pass additional flags or change the settings of your editor. Most notably if you are using gvim then you must pass the -f option to gvim by putting
/usr/bin/gvim --nofork"(if the binary is in
/usr/bin) to the text editor field in settings. If you are using some other editor then please read its manual to find out how to do 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. to bring up the thunderbird’s registry editor.
Don’t write HTML messages! Go to the main window! There you can disable the option “Compose messages in HTML format”.
Open messages only as plain text! Go to the main window!
Works. Use “Insert file…” or external editor.
Gmail (Web GUI)¶
Does not work for sending patches.
Gmail web client converts tabs to spaces automatically.
At the same time it wraps lines every 78 chars with CRLF style line breaks although tab2space problem can be solved with external editor.
Another problem is that Gmail will base64-encode any message that has a non-ASCII character. That includes things like European names.
Proton Mail has a “feature” where it looks up keys using Web Key Directory
(WKD) and encrypts mail to any recipients for which it finds a key.
Kernel.org publishes the WKD for all developers who have kernel.org accounts.
As a result, emails sent using Proton Mail to kernel.org addresses will be
Unfortunately, Proton Mail does not provide a mechanism to disable the
automatic encryption, viewing it as a privacy feature.
The automatic encryption feature is also enabled for mail sent via the Proton
Mail Bridge, so this affects all outgoing messages, including patches sent with
Encrypted mail adds unnecessary friction, as other developers may not have mail
clients, or tooling, configured for use with encrypted mail and some mail
clients may encrypt responses to encrypted mail for all recipients, including
the mailing lists.
Unless a way to disable this “feature” is introduced, Proton Mail is unsuited
to kernel development.