heyy im trying to make a good mailcow server in DigitalOcean.
can someone tell me a bit more about mailgun and sendgrid? idk what they are for and what they do? (this will help alot) Thank you!
These are providers for a Mailrelay or Smart host: https://en.wikipedia.org/wiki/Smart_host
If your provider e.g. blocks port 25 which is necessary to send emails to another mailserver you either need a relay or ask the provider to unblock said port.
Mailrelays are also used to send bulk mails (Newsletter) because they have a good IP reputation