An example method to monitor an email system involves sending a test email to an email server. The email server is to automatically forward the test email to a plurality of email accounts of corresponding domains different from one another and different from the email system. When the test email does not arrive at the plurality of email accounts within a time period, a notification identifying the email server is generated. Other test emails are distinguished from the test email based on checksum values in subject fields of the test email and the other test emails. The other test emails correspond to different ones of a plurality of other email systems being tested for operability. Each checksum uniquely identifies a respective one of the test emails and a respective one of the email systems.