You need to keep the Swedish Pensions Agency (Swedish: pensionsmyndigheten) updated on your address. Unlike some others, they do not get it automatically from Skatteverket!

In 2012, the Swedish Pensions Agency issued a press release pointing out they were lacking the address of more than half the people with pension savings living abroad:

Pensionsmyndigheten har totalt 540 000 pensionssparare som inte är folkbokförda i Sverige. Det innebär att vi har 317 000 pensionssparare som vi inte har adress till och därmed inte kan kontakta.

My translation:

The Swedish Pension Agency administrates 540 000 pension savers who are not resident in Sweden. That means we have 317 000 pension savers of whom we don't have an address and whom we can therefore not contact.

When they do have your address, they will send you the so-called "orange envelope" every year, containing your pension statement. There is conflicting information on the website of the Swedish Pensions Agency. In Swedish they write:

När du bor i ett annat land omfattas du inte av den svenska folkbokföringen. Därför måste du själv anmäla till oss om du flyttar till en ny adress.

(...)

Skicka dina nya adressuppgifter och ditt svenska personnummer i ett undertecknat brev till:

Pensionsmyndigheten
839 77 Östersund
SWEDEN

Vi kan inte ta emot adressändring via fax, e-post eller telefon.

My translation:

When you live in another country you are not included with the Swedish civil registry. Therefore, you must yourself tell us when you move to a new address.

(...)

Send your new address information with your Swedish personal number in a signed letter to:

Pensionsmyndigheten
839 77 Östersund
SWEDEN

We cannot process address change notifications by email.

They write something quite different on the English lanugage pages. Here they write that they do get the address from skatteverket and that you can send an address change by email. I've contacted them to clarify the confusion, but I believe the part about skatteverket is at least not true, because I've kept my address updated with skatteverket myself, and I'm getting letters from Statens tjänstepensionsverk (SPV), but not from the Swedish Pensions Agency; since they're apparently supposed to send an orange envelope every year but I haven't received any since I left Sweden, I don't think that's accurate.

You need to keep the Swedish Pensions Agency (Swedish: pensionsmyndigheten) updated on your address. Unlike some others, they do not get it automatically from Skatteverket!

In 2012, the Swedish Pensions Agency issued a press release pointing out they were lacking the address of more than half the people with pension savings living abroad (most of them foreign nationals who spent some years working in Sweden and then left to go home or to a 3rd country):

Pensionsmyndigheten har totalt 540 000 pensionssparare som inte är folkbokförda i Sverige. Det innebär att vi har 317 000 pensionssparare som vi inte har adress till och därmed inte kan kontakta.

My translation:

The Swedish Pension Agency administrates 540 000 pension savers who are not resident in Sweden. That means we have 317 000 pension savers of whom we don't have an address and whom we can therefore not contact.

When they do have your address, they will send you the so-called "orange envelope" every year, containing your pension statement. There is conflicting information on the website of the Swedish Pensions Agency. In Swedish they write:

När du bor i ett annat land omfattas du inte av den svenska folkbokföringen. Därför måste du själv anmäla till oss om du flyttar till en ny adress.

(...)

Skicka dina nya adressuppgifter och ditt svenska personnummer i ett undertecknat brev till:

Pensionsmyndigheten
839 77 Östersund
SWEDEN

Vi kan inte ta emot adressändring via fax, e-post eller telefon.

My translation:

When you live in another country you are not included with the Swedish civil registry. Therefore, you must yourself tell us when you move to a new address.

(...)

Send your new address information with your Swedish personal number in a signed letter to:

Pensionsmyndigheten
839 77 Östersund
SWEDEN

We cannot process address change notifications by email.

They write something quite different on the English lanugage pages. Here they write that they do get the address from skatteverket and that you can send an address change by email. I've contacted them to clarify the confusion, but I believe the part about skatteverket is at least not true, because I've kept my address updated with skatteverket myself, and I'm getting letters from Statens tjänstepensionsverk (SPV), but not from the Swedish Pensions Agency; since they're apparently supposed to send an orange envelope every year but I haven't received any since I left Sweden, I don't think that's accurate.