Aliases, Forwarding, Auto-Replies, and Sieve Filters: Setup and Examples

Once a company has shared addresses, people going on vacation, and dozens of emails a day, mail needs some structure: who gets messages sent to sales@, who answers clients while a manager is away, and how to keep invoices apart from newsletters. This article is for administrators and experienced users and covers four tools: aliases, forwarding, auto-replies, and Sieve filters.

Alias, forward, or separate mailbox?

These are often confused, but they work differently.

Tool	How it works	When to use it
Alias	An extra address whose mail is delivered to one or more existing mailboxes. An alias has no mailbox or password of its own.	info@, sales@, hr@; old addresses after someone's name changes
Forwarding	A mailbox receives a message and sends a copy to another address, which can be outside your domain.	Temporarily handing mail over to a colleague, sending copies to a manager's phone
Separate mailbox	A full mailbox with its own password, folders, and quota.	When you need to send mail as that address and keep its correspondence separate

Shared addresses: sales@ and info@

A typical setup for a small company: sales@example.uz is an alias, and its mail goes to the personal mailboxes of two sales managers. The benefits:

• No shared password used by several people, which matters for security. See our article on mailbox security.
• When an employee leaves, you just remove them from the alias recipients.
• The address on business cards and your website stays the same when people change.

An alias has one limitation: replies to clients go out from the manager's personal address. If replying from sales@ itself matters, create a separate mailbox and add it to employees' email apps as an extra account.

Forwarding mail

Forwarding is turned on in the mailbox settings in webmail. There are usually two modes: forward a copy and keep the message, or forward without keeping it. Keeping a copy is almost always the better choice, so nothing is lost if the outside address stops working.

Keep a few things in mind when forwarding to outside addresses:

• A forwarded message keeps the original sender, but now your server is the one sending it. Because of this, the recipient's SPF check may fail and the message may go to spam. A DKIM signature usually survives if the message is forwarded unchanged.
• Don't forward all your mail to free mailboxes. A copy of company correspondence ends up outside your control.
• Attackers who gain access to a mailbox often quietly add a forward. Check these settings from time to time.

Auto-reply

An auto-reply sends a preset message in response to incoming mail, for example while you're on vacation. A good auto-reply is short and useful:

• the dates you're away;
• who to contact about urgent matters (a colleague's address or a shared address);
• no unnecessary personal details or mobile numbers unless they're really needed.

A well-behaved auto-reply answers each sender no more than once in a set period and doesn't reply to mailing lists or automated messages. In SOGo webmail, the auto-reply is turned on in the mail settings. See our article on SOGo webmail for details.

Sieve filters

Sieve is a standard language for mail-handling rules (RFC 5228). Rules run on the server at delivery time, so they work the same way in webmail, on a computer, and on a phone, even when your email app is closed. Simple filters are easiest to create in the webmail interface, and more complex ones can be written as a script.

A script consists of extension declarations (require) and if conditions. A message that doesn't match any rule is delivered to the Inbox.

Sorting by subject and sender

require ["fileinto"];

# Invoices from any sender go to the Invoices folder
if header :contains "subject" ["invoice", "bill"] {
    fileinto "Invoices";
    stop;
}

# All mail from a partner's domain goes to the Partners folder
if address :domain :is "from" "partner.uz" {
    fileinto "Partners";
    stop;
}

The stop command ends processing so the message isn't caught by later rules. The folders need to exist beforehand.

Copying sales@ mail to the director

require ["copy"];

if address :is "to" "sales@example.uz" {
    redirect :copy "director@example.uz";
}

The copy extension keeps the message in the mailbox and sends a copy. Without :copy, redirect sends the message on and it won't stay in the original mailbox.

Multiple conditions and large messages

require ["fileinto"];

# Messages over 10 MB from outside senders
if allof (size :over 10M,
          not address :domain :is "from" "example.uz") {
    fileinto "Large";
}

# Newsletters, detected by the List-Id or Precedence header
if anyof (exists "list-id",
          header :is "precedence" ["bulk", "list"]) {
    fileinto "Newsletters";
}

allof requires every condition to match, while anyof requires at least one.

Auto-reply with Sieve

require ["vacation"];

vacation
    :days 1
    :subject "Out of office until October 20"
    :addresses ["ali@example.uz"]
    "I am on leave until October 20. For urgent matters, please contact sales@example.uz.";

:days 1 means each sender gets the auto-reply at most once a day. List every address you receive mail at, including aliases, in :addresses.

Common mistakes

• Forwarding loops: mailbox A forwards to B, and B forwards back to A. Check the chain, especially when aliases are involved.
• A filter "swallowed" important mail because the condition was too broad, like :contains "subject" "a". Start with narrow rules and test them on sample messages.
• A typo in a folder name in fileinto. The message may stay in the Inbox, or the rule may fail to save.
• A forgotten auto-reply after you're back from vacation. Set an end date if the interface allows it.

If you need help with aliases or a Sieve script, message @mycloudsupport.