You need these values to set up your mailbox in an email program such as Thunderbird, Apple Mail, Outlook in IMAP mode or any other client.

Credentials

FieldValue
UsernameYour full email address, e.g. max.mustermann@musterfirma.at
PasswordThe mailbox password
Incoming and outgoing mail serverzimbra.mydc.at

The two most common mistakes are a username that consists only of the part before the @, and your own domain as the server name. Our certificate is issued exclusively for zimbra.mydc.at; with any other name your program reports a certificate error.

Ports

PurposeProtocolPortEncryption
Incoming mailIMAP993SSL/TLS (recommended)
IMAP143STARTTLS
POP3995SSL/TLS
Outgoing mailSMTP587STARTTLS (recommended)
SMTP465SSL/TLS

Outgoing mail always requires authentication with the same credentials. Enable “Server requires authentication” or the equivalent option in your program. Unencrypted connections are not possible; POP3 on port 110 is closed.

IMAP or POP3?

Use IMAP. Folder structure, read status and sent messages stay the same on all devices, and in the Business and Enterprise plans everything is included in our backup. POP3 fetches the messages onto your device and, depending on the setting, deletes them from the server. After that they are only held locally on your device and no longer in our backup.

Message size

A message may be up to 150 MB in size, including attachments. Attachments grow by about a third when they are sent, so a 100 MB file already comes close to the limit. The receiving end may have a lower limit.

Notes on individual programs

Thunderbird
Set the authentication method for incoming and outgoing mail to “Normal password”. Automatic detection occasionally suggests OAuth2, but sign-in then fails.
Apple Mail, iOS, Android
For calendar and contacts, ActiveSync is the better way.
Outlook
Over IMAP, Outlook synchronizes email only. For the full feature set, see Outlook on Windows.

If the connection fails

Sign-in is rejected
Did you enter the full email address as the username? You set a new password under E-Mail Accounts.
Receiving works, sending does not
In most cases, authentication for the outgoing mail server is missing, or port 25 is entered instead of 587.
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