If you try to subscribe to a mailing list and do not get a confirmation email within a few hours, something is wrong. If you used to be subscribed, and stop getting mail, something may be wrong.
A good way to test if something is wrong at your end is to send yourself mail from an outside address (an email account that is not part of your organization), or have a friend at another organization send you mail.
An easy way to see if you are subscribed to a mailing list is to send a query command to the list manager (not to the list itself). For Pensive.Org lists, you can send the command WHICH to the address autoshare@lists.pensive.org, or if your browser is configured with your correct email address, just click here. If you do not get a response within a few hours, something is wrong.
The single most common reason why people cannot receive email from a mailing list (or from anyone outside their organization) is misconfigured anti-spam measures.
Newer versions of sendmail have anti-spam features which are often misconfigured. Sendmail is the most common SMTP server in use today. When misconfigured, these anti-spam measures make it impossible to send mail from outside the organization to anyone in the organization. Even mail to postmaster, which according to Internet mail standards is an address that MUST always work, bounces with a "relaying denied" error.
A very high percentage of people who try and
subscribe to Pensive.Org mailing lists turn out to be in organization
which use a misconfigured sendmail. All mail to them or to their
postmaster bounces. Every day several subscribers of
various Pensive.Org mailing lists (such as the popular qpopper list) get
automatically unsubscribed because all mail to them bounces. In
most cases this is because someone at their organization misconfigured
their sendmail to not accept any mail from outside.
Advice to mail administrators:
Whenever sendmail is upgraded or the rule sets changed, the ability to
send and receive mail must be verified. It is especially important
to test that mail from outside the organization can be sent to
postmaster.