We have been struggling with Sendgrid the last couple of years with black listed ip-addresses, mails ending up in spam and mails blocked by mailservers. We only do transactional mails to our customers but still Sendgrid can not deliver good enough. We have been in contact with support, tweaking the settings but still the same problems.
So we decided to try Postmark. After a couple of weeks testing it works like a a dream - all our mails are suddenly delivered. Everyday and all the time.
The plugin for Postmark in Bubble just supports plain text so we just created our own api-connection with the api-connector. Very easy and straight forward.
If you are used to Sendgrid it takes a while before you understand the logic in Postmark. In Postmark you can create servers for every project, website or customers. With server you have everything separated like templates, activity logs, settings etc.
Just wanted to share this with the community because it saved me a lot of time and headache.