That's spammer speak

I’ve been hearing stories from other deliverability consultants and some ISP reps about what people are telling them. Some of them are jaw dropping examples of senders who are indistinguishable from spammers. Some of them are just examples of sender ignorance.
“We’re blocked at ISP-A, so we’re just going to stop mailing all our recipients at ISP-A.” Pure spammer speak. The speaker sees no value in any individual recipient, so instead of actually figuring out what about their mail is causing problems, they are going to drop 30% of their list. We talk a lot on this blog about relevancy and user experience. If a sender does not care about their email enough to invest a small amount of time into fixing a problem, then why should recipients care about the mail they are sending?
A better solution then just throwing away 30% of a list is to determine the underlying reasons for  delivery issues, and actually make adjustments to  address collection processes and  user experience. Build a sustainable, long term email marketing program that builds a loyal customer base.
“We have a new system to unsubscribe people immediately, but are concerned about implementing it due to database shrink.” First off, the law says that senders must stop mailing people that ask. Secondly, if people do not want email, they are not going to be an overall asset. They are likely to never purchase from the email, and they are very likely to hit the ‘this is spam’ button and lower the overall delivery rate of a list.
Let people unsubscribe. Users who do not want email from a sender are cruft. They lower the ROI for a list, they lower aggregate performance. Senders should not want unwilling or unhappy recipients on their list.
“We found out a lot of our addresses are at non-existent domains, so we want to correct the typos.” “Correcting” email addresses is an exercise in trying to read recipients minds. I seems intuitive that someone who typed yahooooo.com meant yahoo.com, or that hotmial.com meant hotmail.com, but there is no way to know for sure. There is also the possibility that the user is deliberately mistyping addresses to avoid getting mail from the sender. It could be that the user who mistyped their domain also mistyped their username. In any case, “fixing” the domain could result in a sender sending spam.
Data hygiene is critical, and any sender should be monitoring and checking the information input into their subscription forms. There are even services which offer real time monitoring of the data that is being entered into webforms. Once the data is in the database, though, senders should not arbitrarily change it.