Older email client can't send email

[jonknoll]

We have an older email client. Papercut v5.4 receives our emails just fine, but after v5.4 they never get through. Looking at the packet captures, the recipient gets rejected. It appears that the TO and FROM email addresses must be inside angle brackets my@email.com for the address to be accepted. Older SMTP clients don't do this. For backwards compatibility, can the logic be changed back to still accept the older format with no angle brackets?
with < >

without < >

[1Jesper1]

@jonknoll I see in version 5.4.1 another SMTPServer has been used: 5.4.0...5.4.1#diff-b86fde319b108f5aad77b46b8f12fc209239ce28d1ff7ad97afeb7908983afc7
https://github.com/cosullivan/SmtpServer Maybe you can ask for compatibility in that repository?

[1Jesper1]

Because of the checks on the lessthan and greaterthan symbols https://github.com/cosullivan/SmtpServer/blob/683cd9609f156b0f50d29139e97c0daef1eb3d52/Src/SmtpServer/Protocol/SmtpParser.cs#L849

[cosullivan]

@jonknoll do you know what those older mail clients they are by any chance?

The original SMTP spec (rfc821) was produced in 1982 and even that contained the literal form of the angle brackets in the paths, so I am surprise that there would be mail servers that allowed it.

I will look at adding a way for you to override the default behavior rather than for me to modify the server itself to support something that isn't in the spec (that I have seen anyway).