Antivirus can alter an outgoing message and invalidate its DKIM signature

If you DKIM-sign e-mails you send with MailBee.NET Objects, you can face the issue of DKIM signatures being incorrect. This happens if you also have an antivirus which intercepts all SMTP traffic and alters outgoing e-mails with adding its own signature (something like “No virus found”). That signature may even be not visible to the end user (if it’s placed in a separate MIME part) but DKIM and DomainKeys signatures earlier added by your application will still become invalid.

To fix this, you’ll need to disable adding signatures by your antivirus (at least for legit e-mails). If the antivirus program does not provide this option and you cannot replace it with another program, DKIM/DomainKeys signing on the client side won’t work. The only option in this case will be server-side signing (it must be supported by your mail relay server). This option is, however, outside the scope of MailBee.NET Objects.

Antivirus can alter an outgoing message and invalidate its DKIM signature

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