I've split another conversation here, because it might help others. (And side topics like this make emails into novels.)
Why Not Use You Own Server?
You should avoid using a webserver as a mail server, except for sending personal/business emails. As you say, "trivial" use. Otherwise you'll likely find the server on multiple blacklists, which can harm its reputation, and even affect SEO of the sites on it. Yes, this means email can have a negative effect on the site, too! It's not just email lists that can harm the domain reputation.
In addition, your non-list business emails are also treated like they're spam.
There's several reasons why this happens:
(A) Somebody opts in to your mailing list, but reports the message as spam instead of opting out. This can happen because they're lazy, because they forgot they signed up, or because the email didn't provide the information that they had hoped. (Some unethical affiliate marketers even bait-and-switch those that sign up! In that case, I'd agree, it's spam.)
(B) If the sign-up email is no longer functional, repeated attempts at delivery may get reported to RBLs. In some cases, simply submitting once, and surpassing a threshold for failures automatically lands it on a list. This is very common among ISPs like Comcast, Charter, AOL and Earthlink. Some emails even find their way onto spam traps, often because of backscatter.
(C) Some mail servers have hidden limits for receiving email. For example, if a new server suddenly sends thousands of emails, that legitimate activity can lands it on a blacklist. This is also often done by ISPs.
(D) The server gets hacked because of lazy or poor security policies regarding passwords. While this isn't specific to sending large email lists, it can affect any server where a mail service in enabled.
Removing an IP from a RBL (DNSBL) is a great big PITA, to be frank. Because of this, virtually all hosts charge "clean-up" fees to do this. Other just suspend a person and tell them to go away. In fact, hosts only want to really deal with their own shared/reseller servers -- not dedicated or VPS. That's up to the owner, or they'll help with removal for a fee ($$$).
Trying to rotate an IP because it's now dirty will also result in fee being charged by hosts. Many bar the person from ever being a customer again. If it's tagged by an RBL, it's going to be up to you to clean it up, both by contacting the blacklist owners, and by auditing your own list to see how it happened. Otherwise, it'll just happen again. Like the hosts, blacklists often charge a fee ($$$) for removal.
Some RBLs will refuse, and you'll have to wait it out (anywhere from 2 to 8 weeks).
Newsletter / SMTP Services
SMTP services work with blacklist owners to keep themselves off the lists. They send high volumes of email, and in most cases it less than a % of 1% that cause problems. Furthermore, spammers are cheap. They'd rather hack a server for free, or buy some cheap shared/VPS hosting somewhere (often from clueless kiddie hosts).
CritSend and
Mandrill are two of my favorite. On the cheaper end, you can use
Amazon SES.
You can also use a server like
Constant Contact, Aweber, MailChimp, etc.
These are really more of a newsletter service, for scheduling either monthly or daily emails. Many also have auto-responders, and they have a stringent double opt-in process to be 100% compliant with U.S. law (CAN-SPAM Act). Quite a few affiliate marketers use these, as opposed to homemade method of assembling email lists, In fact, I'd say that most use it.
Conclusion
You really have to be careful when you send out a lot of email.
And for the sake of number, let's say 10,000+. If you have ten thousand people that signed up for your list, even a 1% response rate is going to yield 100 customers. Depending on the cost of the product or service, it should easily pay for the costs of having a mail service for the lists.
Same for webservers. I can't help but laugh at the folks over at Warrior Forum that claim to have thousands of dollars per day of income (revenue), yet host the sites on a $10 account at EIG. When the server is down, they cry en masse. "Whoa is me, I'm losing a zillion dollars because my Godaddy site is down!"
What I'm getting at is both email and servers need to be commensurate for the products/services they represent. If it's a big list, it needs the SMTP or newsletter service. If it's a big site, it needs a bit dedicated or maybe VPS server. Trying to skimp on these things is not going to work long-term,
