Emacs’ users tend to like to do everything in it as I do. A frequent desire is to be able to read emails in it. A popular option is Gnus.
Gnus is a beast it can do a lot of things from newsgroups, to RSS to emails. So configuring and using it can be a bit scary at first.
There’s a really widespread misinformation about Gnus. I thought for long it was true but it comes out it wasn’t.
This is about using multiple SMTP servers seamlessly for sending
emails. I always read you have to use external tools such as
MSMTP with specific configuration to make
it acts as a proxy between your software and your multiple remote
SMTP. Some other advice you to use a homemade function to play with
message fields and hook it via
Some will even tell you to hack your
But hey, Gnus is there since the nineties. Someone must have think of a solution and it must be built-in!
I stopped searching blog posts and Stack Overflow and read the manual entry which clearly states that you can set up a complex workflow using multiple SMTP servers.
This works by using posting styles which is a way to instruct Gnus of how you want to prepare your email (headers, body, signature) according to the context.
Before digging into it I’d like to explain my IMAP settings because it’s tightly related to how we’re going to setup SMTP.
So let’s take a look at the “select-method” definitions. This is where we tell Gnus about our IMAP servers, their local name and how they must behave:
(setq gnus-select-method '(nnnil nil)) (setq gnus-secondary-select-methods '((nnimap "home" (nnimap-address "imap.gmail.com") (nnimap-server-port "imaps") (nnimap-stream ssl) (nnir-search-engine imap) (nnmail-expiry-target "nnimap+home:[Gmail]/Trash") (nnmail-expiry-wait 'immediate)) (nnimap "work" (nnimap-address "imap.gmail.com") (nnimap-server-port "imaps") (nnimap-stream ssl) (nnir-search-engine imap) (nnmail-expiry-target "nnimap+work:[Gmail]/Trash") (nnmail-expiry-wait 'immediate))))
nnnil which is a NOOP back-end. I
prefer to set all the accounts in the same place
In this variable I have declared two IMAP servers. The first one will
be known locally as
home and the second one as
Both are using Gmail, so we have to find a way to distinguish these to account to provide credentials.
The standard Unix way to share credentials across software is to
store them in
~/.authinfo file. In my case I use
so my credential are encrypted with GPG and no one but me can read it.
Here is the content of
machine home login email@example.com password my_pasword port imaps machine work login firstname.lastname@example.org password my_other_password port imaps
Now Gnus can read this file to get the credentials and log on the IMAP
servers. Gnus know how to bind a given credential to a specific
account because their share the same name
Ok from now on, we can get emails from Gnus through these two email accounts.
Now it’s time to configure these accounts to send emails using their respective SMTP server / credential.
Just for the sake of clarity, I do use the same IMAP / SMTP addresses for both accounts in my situation but this technique would work the same way with two accounts on two different email providers.
All the magic happens by taking advantage of Gnus posting styles:
;; Reply to mails with matching email address (setq gnus-posting-styles '((".*" ; Matches all groups of messages (address "Nicolas Cavigneaux <email@example.com>")) ("work" ; Matches Gnus group called "work" (address "Nicolas Cavigneaux <firstname.lastname@example.org>") (organization "Corp") (signature-file "~/.signature-work") ("X-Message-SMTP-Method" "smtp smtp.gmail.com 587 email@example.com"))))
The first line with the
.* is kind of catch-all rule which tells
Gnus that no matter what is the group I’m in, my sender email address
is going to be
For those who are not familiars with Gnus, a group is just an IMAP folder.
Then the second rule tells Gnus, if the current group matches anything
work in it then I want to handle my outgoing emails
differently. My sender address is going to be
organization header is going to be
Corp, my automatically inserted
signature at the bottom of the email is going to be read from
~/.signature-work file and here happens the magic we use a
special header that Gnus and
message-mode understand called
X-Message-SMTP-Method that was designed for this exact purpose,
being able to specify an alternative SMTP server to use. So we specify
that we want to use
smtp protocol using the address
587 and that the user account to use is
There’s one last thing to setup and you’ll be good to go. You need to
provide your SMTP credentials. Once again it takes place in the
machine smtp.gmail.com login firstname.lastname@example.org password my_password port 587 machine smtp.gmail.com login email@example.com password my_other_password port 587
By searching the server name / username Gnus will be able to know the right credential to use.
Moral of the story, when it comes to Emacs you should always read the official doc first since most of the time you’ll find the info you need.