http://promberger.info/linux/2009/07/23/mutt-limit-or-search-by-date/

The following will not work:

~d < 1w

Use this instead:

~d <1w

Also, remember mutt uses the "AND" operator by default, so do not add & or &&
to combine searches using AND. Instead, just string them together. Say you want
to see all mail to, from, or cc a specific address group, sent in the last
seven days, do l for limit, or / for search, followed by:

%L groupname ~d <1w

Addendum

It seems you cannot, by the way, combine the relational < or > searches with an
absolute date. You can, however, add an error margin to an absolute date,
usually achieving what you want to do. The error margin can be before (-),
after (+), or both, using *. Like this:

Up to one month before date:

~d 30/10/08-1m

Up to five days after this date of the current year:

~d 04/05+5d

One week before and after date:

~d 27/02/2009*1w

------------------------------------------------------------

http://www.mutt.org/doc/devel/manual.html#date-patterns

3.4. Searching by Date

Mutt supports two types of dates, absolute and relative.

3.4.1. Absolute Dates

Dates must be in DD/MM/YY format (month and year are optional, defaulting to
the current month and year). An example of a valid range of dates is:

Limit to messages matching: ~d 20/1/95-31/10

If you omit the minimum (first) date, and just specify “-DD/MM/YY”, all
messages before the given date will be selected. If you omit the maximum
(second) date, and specify “DD/MM/YY-”, all messages after the given date will
be selected. If you specify a single date with no dash (“-”), only messages
sent on the given date will be selected.

You can add error margins to absolute dates. An error margin is a sign (+ or
-), followed by a digit, followed by one of the units in Table 4.6, “Date
units”. As a special case, you can replace the sign by a “*” character, which
is equivalent to giving identical plus and minus error margins.

Table 4.6. Date units
Unit	Description
y	Years
m	Months
w	Weeks
d	Days

Example: To select any messages two weeks around January 15, 2001, you'd use
the following pattern:

Limit to messages matching: ~d 15/1/2001*2w

3.4.2. Relative Dates

This type of date is relative to the current date, and may be specified as:

    >offset for messages older than offset units

    <offset for messages newer than offset units

    =offset for messages exactly offset units old 

offset is specified as a positive number with one of the units from Table 4.6,
“Date units”.

Example: to select messages less than 1 month old, you would use

Limit to messages matching: ~d <1m