Configuration of Mail Clients

1. Introduction [menu]

Using mail clients has it’s advantages compared to web interface, it is however necessary to install and properly configure the mail client.

Office 365 and mail clients in 2018.

According to the statistics from Office 365, users most commonly use mail clients on mobile devices. Applications Outlook for Windows and Outlook for macOS follow – both are a part of the office suite Microsoft Office (most users have 5 free licenses). Other clints for mobiles have lesser representation, there are few desktop clients using the IMAP protocol.

The following text describes the configuration of mail clients for access to the school’s mailboxes. The means of access depend on whether you have your mailbox in Office 365 or InSIS – you specify which mailbox you use by setting the distribution server.

2. Mailbox in Office 365 [menu]

2.1 Outlook for Windows/macOS

You can install Outlook for Windows or macOS from Office 365.
After installation, it’s necessary to add the account. It’s usually sufficient to enter login name and password.

user name form:
password: school_password

I recommend saving the password so that you won’t have to enter it again each time you access your mail.

Enter <user_name>, not e-mail address in the form of <first_name.surname>; – this will be filled automatically after the connection is established. If you enter e-mail adress, the client will not be able to log into your account.
>> click to view instructions to configure Outlook in Windows <<
  1. After installing Office from Office 365, run the Outlook application. You will be asked for username, including
  2. In the following step, enter your password. I recommend to check the option Remember credential, so that you won’t have to enter password each time you run the Outlook application.
  3. In the following screen, you can see that the account has been added successfully. It’s possible to add additional mailboxes (they shouldn’t be from Office365) or to view instructions to install mobile Outlook. I recommend not to add any accounts and press the Finish button:

Occasionally, Outlook won’t remember your password the first time and will require you to enter your password again after you run the application again. Outlook will remember your password then.

2.2 Microsoft Outlook for Android/iOS

Microsoft Outlook for Android a Microsoft Outlook for IOS (iPhone) are freely available in the relevant application stores. After installation, it’s necessary to add your account. It’s usually sufficient to enter login name and password, just like in case of Outlook for Windows/macOS.

user name syntax:
password: school_password

2.3 Other mobile mail applications (ActiveSync)

We recommend using two mail applications on mobile phones – one for your private mail (i.e. with or and one for school mail (i.e. For school mail, you can also use other mail clients beside Microsoft Outlook, see for example Best Emaill Apps 2018. Personally, I use paid application Nine on my mobile for school mail.

While configuring these applications, you usually choose type Office 365 or Exchange or ActiveSync and the following details:

user name syntax:
password: school_password

Office 365 and Google mail client for Android

2.4 Other mail applications in Windows, MAC OS or Unixu (IMAP and SMTP)

In Windows or MAC OS operating systems, you can also use other mail clients, see for example 10 Best Desktop Email Clients for Mac and Windows. There is no Outlook for Unix.

These applications use the IMAP (viewing mails, moving between folders, deleting) and SMTP (sending mail) protocols. For mailbox in Office 365, the following parameters are used:

Office 365
server name port number requires SSL/TLS? user name syntax
IMAP server 993 yes, e.g.
SMTP server 587 (STARTTLS) yes, e.g.

Configuring Thunderbird to read mail from InSIS or Office 365

3. Mailbox in InSIS [menu]

Use a combination of IMAP and SMTP protocols. To read mail through IMAP, you must enable remote mail reading first (Mail box -> Settings -> Allow distant mail reading). Then, while configuring your mail client, use the following parameters:

InSIS server name port number requires SSL/TLS? user name syntax
IMAP server 993 yes user_name, e.g. abcd01
SMTP server 587 (STARTTLS) yes user_name, e.g. abcd01

Configuring Thunderbird to read mail from InSIS or Office 365

4. Mail clients using IMAP protocol [menu]

In every mail program, it’s necessary to define mail account – set a name (e.g. Luboš Pavlíček), mail address (e.g. or, mail server with your mailbox (IMAP server, POP server) and mail server for outgoing mail (also SMTP server). For reading new mail, you can use POP and IMAP protocols (it also depends on which protocols are supported by the particular mail server), while the SMTP protocol is used for sending mail. Servers for incoming and outgoing mail are often different!!! In the case of most mail clients, it’s possible to define more mail accounts.

Security level for incoming and outgoing server is also configured separately. In general, we distinguish between the following security levels:

  1. anonymous access – only used for outgoing mail (SMTP server), where the server doesn’t require username or password. Usually, access is restricted only to some addresses or it’s not available at all. VŠE does not allow anonymous access!
  2. authorization with name and password with SSL/TLS secured communication. This secure mode is supported by all school mail servers.
  3. certificate based authorization – this security level is not currently supported at school and won’t be further described.

Reading mail is possible through the following protocols:

  • IMAP (SSL/TLS port 993) – this protocol allows you to work with individual folders. If configured properly, it’s possible to ensure that both the client and the web interface will have access to the same e-mails in all folders (with varying comfort, of course).
  • POP (SSL/TLS port 995) – this protocol can only download new mail, it doesn’t allow access to folders. We do NOT support for school servers.

For sending mail, SMTP protocol is used. Given the fact that this protocol can be easily abused for sending SPAM, there are many restrictions put in place:

  1. authentication is required (entering name and password) in secure channel (port 465 či 587),
  2. e-mail size is restricted (approx. 15 MB) – all attachments are included in calculation of e-mail size,
  3. number of recipients is limited.

In Office 365, there are further limits.