For most use cases, email has long since replaced conventional letter mail as a means of communication. Companies in particular handle a large part of their correspondence by email, because it speeds up processes compared with snail mail; also, you can send arbitrary attachments.

However, modern email programs can do more than read, write, and send messages. They can also integrate the messages into corporate workflows. The email program often serves as a personal assistant, because it usually also manages contacts and appointments and can forward data to enterprise software through various interfaces.

Additionally, email communication can be automated, if required (e.g., allowing employees to send a vacation message to their communication partners). In this article, I take a closer look at what the common graphical email clients do in terms of user ergonomics, security, and extensibility.

Functionality

The heart of all email clients is the connection to the mail server. The client uses POP3 or IMAP to retrieve incoming messages from the server. Whereas the POP3 protocol retrieves messages from the server and moves them to the client, the IMAP protocol keeps the messages on the server, which allows mail to be viewed and edited without being tied to a specific computer. The email client also archives incoming email, so that it can be accessed, even without a connection to the server. Email is sent over the SMTP protocol, with convenient features such as a queue for outgoing mail.

Email clients can usually manage several accounts simultaneously and independently of each other. Additional functions, such as address books or conversion routines provided by the program, can be used with all accounts. Some programs offer prioritization of outgoing email and can send unimportant items with a time delay if you have a large volume of messages.

Another important criterion when using an email client is security. Usually, the message transport is encrypted, for which the TLS protocol is usually used. The authenticity of messages can be guaranteed by signing; however, complete end-to-end encryption of messages requires a corresponding infrastructure with private and public keys, which is the only way to guarantee that confidential information really remains confidential.

Professional email clients additionally implement various filter and search routines, which can be used to track down any email related to a specific keyword or phrase. It is often possible to combine several terms with each other, which enables a more targeted search. Moreover, the programs help filter out unsolicited email, known as junk or spam, from the Inbox. Specialized back ends such as SpamAssassin, Bogofilter, or Bsfilter are usually used for this purpose. Their filter lists and detection routines are constantly updated, which ensures a high hit rate.

Claws Mail

Claws Mail [1] was created in 2005 as a fork of Sylpheed [2]. The cross-platform software uses the GTK+ toolkit and can be found in the software repositories of most common distributions. Additionally, a Flatpak package allows cross-distribution installation.

The modular program, written in the C programming language, can be extended with plugins. After the first start, the software calls up a wizard to carry out a basic configuration. The primary window then opens, looking a bit old-fashioned (Figure 1).

Figure 1: The program window in Claws Mail is visually rustic, but functional.

The most important controls are found at the top in a horizontal buttonbar. A folder tree on the left lists the various mail categories, and a large workspace on the right lets you read incoming email. Additionally, a conventional menubar appears at the top of the screen.

Clumsy

Claws Mail has some weaknesses in its configuration routines. The account settings are entered under Configuration , with quite extensive dialogs for each action. Sometimes settings are unnecessarily spread over several dialogs, so, for example, the options you need for a new account cannot be configured in a single operation. A separate category for today's standard transport encryption and port numbers that deviate from the default ports must also be set in a separate dialog.

Like most modern email clients, Claws Mail has an integrated database of predefined providers. With its help, you create a new account by clicking Configuration | Create new account ; after entering the email address of the new account under Server information , you should click Auto-configure . The program uses the database to determine the valid server data for incoming and outgoing mail and configures the details accordingly. It also creates a folder structure.

In the test, automated creation of a new account with various freemail providers such as GMX and Web.de did not work. To integrate such accounts into Claws Mail, you have to enter the respective server addresses for incoming and outgoing mail manually, anyway (Figure 2). The same applies to the associated port numbers and the respective method of transport encryption. For some providers, you need to enable the desired account manually in their web interface for use with external email clients with the IMAP and POP3 protocols.

Figure 2: To set up a new account in Claws Mail, you need to work your way through several dialogs.