swaks
Swiss Army Knife SMTP, the all-purpose SMTP transaction tester.
TLDR
Deliver a standard test email to user@example.com on port 25 of test-server.example.net
$ swaks --to [user@example.com] --server [test-server.example.net]
Deliver a standard test email, requiring CRAM-MD5 authentication as user me@example.com. An "X-Test" header will be added to the email body
$ swaks --to [user@example.com] --from [me@example.com] --auth [CRAM-MD5] --auth-user [me@example.com] --header-X-Test "[test_email]"
Test a virus scanner using EICAR in an attachment. Don't show the message DATA part
$ swaks -t [user@example.com] --attach - --server [test-server.example.com] --suppress-data [path/to/eicar.txt]
Test a spam scanner using GTUBE in the body of an email, routed via the MX records for example.com
$ swaks --to [user@example.com] --body [path/to/gtube_file]
Deliver a standard test email to user@example.com using the LMTP protocol via a UNIX domain socket file
$ swaks --to [user@example.com] --socket [/var/lda.sock] --protocol [LMTP]
