You send a message to someone and never get a reply and later they tell you they never saw it. Someone claims to have sent you a message, but you never received it. A library user signs up for the library newsletter, but they never get it. Missing messages are like lost socks — they get into the system and then simply disappear. Where do they all go?
Some may genuinely get lost out in the Internet somewhere, and some get trapped in overzealous spam filters. But I think a lot of messages are sent and delivered to e-mail accounts that were never closed but are no longer active. If the accounts were closed, you’d get a bounce message and know there was a problem, but many people these days have several semi-abandoned e-mail accounts that they seldom check anymore and may have forgotten. Systems like Gmail provide so much storage that accounts rarely reach the limit and start bouncing mail, so you can be sending mail to someone for years without realizing that they’re not receiving it.
When colleagues, friends, patrons, anyone seems not to be getting mail from you or your library (including notices from the Millennium, NextReads and other e-mail newsletters, hold notices from OverDrive, etc.) here are the first two things I would do:
1. Ask them for their current e-mail address, and see if it’s the one we’re using.
2. Ask them to check to see if the message is being trapped in their spam filter. They may or may not be able to do this, depending on their e-mail provider, options, etc., and they may need to contact their system administrator for a business or school account or the help system for an account on a site like Gmail or YahooMail.
You can also send a test message to confirm that the address itself is working and that they can receive messages you send individually. The problem is that newsletters, overdue notices and other messages from the library may look like bulk mail to the spam filters and get sent straight to a spam folder or even just deleted.
Most systems will allow users to whitelist the e-mail address of the sender so these messages will be delivered, but you’ll need to provide people with that address. For example, in NOBLE our NextReads newsletters are sent by this address: firstname.lastname@example.org. it’s a good idea to keep a list of all the e-mail addresses that get used by library services so you can help users troubleshoot spam problems.
As for the lost sock problem, sorry, you’re on your own!