Aerc with Interimap

While using a mixture of Thunderbird and Evolution since the beginning of (my) time, I’m recurrently tempted by seemingly faster alternatives running inside the terminal. After trying Mutt with no long term success due to it’s complex configuration, I stumbled multiple times over aerc, which was initially started by Drew DeVault, a developer I like for his many great projects.

Until recently I tested aerc either via offlineimap and a local maildir or via a pure IMAP connection. The former makes E-Mail readable without an active Internet connection, however folders of big mailing lists slow down aerc and offlineimap doesn’t sync very fast overall. The IMAP option works amazing, except for the missing offline feature, which comes in very handy at times.

Luckily a friend let me know about interimap, which works similar to offlineimap, but uses a local dovecot instance to handle E-Mail storage and is much faster. The setup is fairly simple and well described on the authors website. It describes how to use interimap with dovecot via a wrapper script, so no permanently running instance of dovecot is required. Instead of connecting on localhost:993 it uses doveadm which executes imap.

The sync process works as fast as excepted and within a few minutes I had all my emails locally available. In the last step the interimap author describes a setup with Mutt, while I’d like to use aerc for its simplicity.

Configuration

Using aerc with the interimap wrapper script wasn’t as easy as I executed. Mutt does support a tunnel command which allows to run a script before connecting to a IMAP server. As for now aerc, which uses internally go-imap, doesn’t offer this feature. Using the maildir of dovecot wasn’t a real alternative for me, as it would slow down aerc again on long lists.

So I looked into the code of go-imap to add a tunnel feature, just to realize that socat does exactly what I need. Instead of modifying any code, I just connect the wrapper script to port localhost:10993:

socat TCP-LISTEN:10993,reuseaddr,pf=ip4,fork exec:/home/user/.local/bin/dovecot-imap

In the aerc configuration I use a insecure IMAP connection:

source = imap+insecure://localhost:10993

That’s all it takes to have an extremely responsive and offline available aerc setup!

Multiple accounts

It becomes slightly trickier with multiple accounts. The wrapper script and dovecot both use prefixes for mailboxes (RFC3501 6.3.8), meaning a single connection contains multiple email accounts. By filtering single mail accounts are connected as view. This feature is also implemented in go-imap, however not yet supported in aerc.

Instead of using the prefixes, I used the folder option with a trivial RegEx:

# accounts.conf
[foobar]
folder = ~foobar/*
default = foobar/INBOX
copy-to = foobar/Sent

[barfoo]
folder = ~barfoo/*
default = barfoo/INBOX
copy-to = barfoo/Sent

This way only folders prefixed with the selected account are shown, even though both mail accounts contain the exact same email. A cleaner solution would be to request only correctly prefixed folders from dovecot instead of hiding non-matching folder names, but it works for now. All other folders like default and copy-to have to be manually prefixed with the same prefix chosen for interimap and dovecot.

Cosmetic workaround

With the configuration described above, all folders listed are prefixed with the account name, which is a waste of space. Until real prefix handling is implemented in aerc I added patched the dirlist formatting so that the first 8 characters are removed, coincidently the length of all my accounts.

diff --git a/widgets/dirlist.go b/widgets/dirlist.go
index aca1491..9617a80 100644
--- a/widgets/dirlist.go
+++ b/widgets/dirlist.go
@@ -148,7 +148,7 @@ func (dirlist *DirectoryList) getDirString(name string, width int, recentUnseen
                                        doRightJustify(name)
                                        rightJustify = false
                                }
-                               formatted += name
+                               formatted += name[8:]
                                percent = false
                        }
                case 'r':

This is clearly a very subjective patch. I’ll try to get more familiar with the codebase and maybe propose a patch implementing real prefix handling.