When non-English characters (for example, Æ, Ø, Å) are used in the From Name field of an EXM message, they might be replaced with the à character in the received message. The issue is related to the wrong decoding of the mentioned symbols during the message sending. This applies to EXM 3.4.0 - 3.4.2.
To resolve the issue, download and install the patch compatible with the affected product version found on this page:
https://github.com/SitecoreSupport/Sitecore.Support.155609/releases