Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - IT Service Group (RBG)

Sending and Receiving E-mails

E-mail, Limits, Quotas, Ports

Inhalt

General Information

Sending E-Mail - SMTP with Authentication

E-Mail-Adresses

Encryption and Signing (Certificates)

Threat Scanning

FAQ

Troubleshooting

General Information

Every employee and student at the Department of Computer Science with a valid account in the department's network also has an e-mail address attached to his account:

<account>@informatik.hu-berlin.de

Furthermore the plain text name entered in the Passwd can be used to form an e-mail address:

<given name>.<surname>@informatik.hu-berlin.de

provided the combination of given name and surname is unambiguous.

E-mail can be sent and received on every computer in the department's network.
The size of a single e-mail message is limited to 20 MB.
The maximum number of recipients per e-mail message is 100. All addressees in "To-", "Cc-" and "Bc" header are falling under this limit. If addressing a private e-mail-list, each member of the list will be counted as single recipient.

The mailboxes (incoming e-mail, private e-mail boxes) for all students and employees are located on the mailserver mailbox.informatik.hu-berlin.de.
IMAP/POP server (Dovecot 2.2) runs on the mail server mailbox.informatik.hu-berlin.de, which allows for users to access their e-mail remotely.

The IMAP/POP-server support the following protocols for reading e-mail: imap, imaps, pop3 and pop3s. It is recommended to use imap (Port 143 with STARTTLS), imaps (Port 993 with SSL/TLS) and pop3s (Port 995 with SSL/TLS). Authentication is done through normal authentication methods, no "secure authentication".

Please note: User trying to access the mailserver from IP-addresses that have no valid DNS-address, for example
bit-side.com (87.193,...)
callax-network.net (83.133....),
celox.de (212.60.251...),
crnagora.net (85.94....,
htel.de (83.242....),
ptt.yu,
qsc.de (87.193....),
superkabel.de (88.134...),
tele2.de,
versanet.de (87.123....)
will not be able to use the e-mail-services (imap, imaps, pop3, pop3s) nicht nutzen!

Sending E-Mail - SMTP with Authentication

The department's mailserver support SMTP with authentication (port 587). With an authenticated SMTP connection, the relay function is supported, i.e. the e-mail client can send e-mail to any destination address. The sender's address ("From:") must be his or her own address at the department (institute). The user's normal UNIX-account is used for authentication. PLAIN and LOGIN are supported as authentication methods. Since both, the UNIX account and its associated password are sent over the network in plain text, a STARTTLS-secured connection is strongly recommended for port 587.

There is no SPAM filtering or greylisting for e-mails delivered through port 587.

Some of the older e-mail-clients do not support SMTP connection with STARTTLS. As workaround SMTP with authentication at port 465 may be used. It is mandatory to secure the connection with SSL/TLS. The service is discontinued. There is no SPAM-filtering or greylisting for e-mails delivered through port 465.

E-mail clients uncapable of supporting either STARTTLS or SSL/TLS to secure SMTP connections must not be used!

E-Mail-Adresses

The e-mail address of an employee or student of the institute usually corresponds to their account name or first name and last name separated by a "." . In case of doubt the assigned account name may be daoublechecked by executing the following command:

ldapcat passwd | grep Doe

on a computer in one of the pc-pool-rooms.

Encryption and Signing (Certificates)

E-mail ceritificates may be requested for all HU-e-mail addresses here: CMS.

Threat-Scanning

Incoming e-mails on the department's mailserver are scanned for known threats. If a threat is found, the e-mail will be rejected and the sender will be informed accordingly. The checks are carried out by "ClamAV" (update frequency: every 2 hours).

FAQ

The E-mail cannot be sent due to exceeding the size limt for attachments.

From the department's e-mail address messages upt to a total size of 20 MB may be sent and received. Other providers may have lower limits and therefore reject the message. Please use the Storage Service by CMS and forward the link only.

Troubleshooting

If you have problems with sending or receiving e-mail on your informatik mail account, please contact the IT-Service Group . They will also be able to find out whether a host has been blocked because of spam-mail.