chore(mail): #132 mail comparions

Readme.md

@@ -35,3 +35,78 @@ As of 2024 there are 4 options:
 Even though I would really implement authentication myself, I think OAuth2 with external providers is the best bet. Especially because my reasoning is privacy, which most people just don't care about enough. Using this approach, adding in a keycloak is possible without breaking changes at a later point, as long as I keep the Google Sign In.
 
 
+### Email
+
+For Email verification, etc. a mail server is needed, that can send a whole lot of mails. Aditionally, a mail account is needed for incoming mails. I thought about self hosting, but unfortunatly this is a hastle to maintain. Not only you have to setup a mail server, which is not as easy as it sounds, you also have to "register" your mail server for diffrent providers. Otherwise you are not able to send and receive emails. Thus, the first external service is needed.
+
+#### Requirements
+
+- Having a normal mail address to send and receive mails
+- Sending transactional mails and newsletters
+- free tier is optimal. So ramp up cost should be as minimal as possible
+
+#### Options
+
+##### AWS SES
+
+Cost: 0.10$ / 1.000 mails
+Free Tier: 100 mails / day, for the first 12 mongths
+
+Pros:
+    - AWS is a big player in the market
+Cons:
+    - AWS is a big player in the market
+
+##### Mailgun
+
+Cost: 15$ / 10.000 mails => 1.5$ / 1.000 mails
+Free Tier: 100 mails / day
+
+##### Sendgrid
+
+Cost: 19.95$ / 50.000 mails => 0.4$ / 1.000 mails
+Free Tier: 100 mails / day
+
+##### MailerSend
+
+Cost: 1.000 mails / month
+Free Tier: 100 mails / day
+
+##### Postmark
+
+Cost: 15$ / 10.000 mails => 1.5$ / 1.000 mails
+Free Tier: 100 mails / month
+
+##### Zohoo
+
+##### Mailjet
+
+
+##### Mailchimp
+
+##### MailerLite
+
+##### Elastic Email
+
+##### SparkPost
+
+##### Twilio SendGrid
+
+
+##### Mailosaur
+
+##### Mailtrap
+
+##### MailSlurp
+
+##### MailHog
+
+##### MailDev
+
+##### MailCatcher
+
+##### Mailtrap
+
+
+
+