| LiveIntent | 543 | https://www.liveintent.com |
| EmailJS | 434 | https://www.emailjs.com |
| SmtpJS | 144 | https://smtpjs.com |
| Mailman | 111 | https://list.org |
| Doppler | 101 | https://www.fromdoppler.com |
| Envoke | 57 | https://envoke.com/ |
| Salesforce Marketing Cloud Email Studio | 12 | https://www.salesforce.com/products/marketing-cloud/email-marketing |
| Mailercloud | 9 | https://www.mailercloud.com/ |
| Xverify | 8 | https://www.xverify.com |
| iEntry | 8 | https://www.ientry.com |
| Mailmunch | 5 | https://www.mailmunch.com |
| Sendtex | 1 | https://sendpad.com |