Using the following, very basic line of code:
new Aspose.Network.Mail.DnsMailClient().Send( message );
…we get the following failure about 50% of the time:
"<!–[if gte mso 9]>
<w:WordDocument>
<w:View>Normal</w:View>
<w:Zoom>0</w:Zoom>
<w:TrackMoves/>
<w:TrackFormatting/>
<w:PunctuationKerning/>
<w:ValidateAgainstSchemas/>
<w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid>
<w:IgnoreMixedContent>false</w:IgnoreMixedContent>
<w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
<w:DoNotPromoteQF/>
<w:LidThemeOther>EN-US</w:LidThemeOther>
<w:LidThemeAsian>X-NONE</w:LidThemeAsian>
<w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript>
<w:Compatibility>
<w:BreakWrappedTables/>
<w:SnapToGridInCell/>
<w:WrapTextWithPunct/>
<w:UseAsianBreakRules/>
<w:DontGrowAutofit/>
<w:SplitPgBreakAndParaMark/>
<w:DontVertAlignCellWithSp/>
<w:DontBreakConstrainedForcedTables/>
<w:DontVertAlignInTxbx/>
<w:Word11KerningPairs/>
<w:CachedColBalance/>
</w:Compatibility>
<w:DoNotOptimizeForBrowser/>
<m:mathPr>
<m:mathFont m:val=“Cambria Math”/>
<m:brkBin m:val=“before”/>
<m:brkBinSub m:val="–"/>
<m:smallFrac m:val=“off”/>
<m:dispDef/>
<m:lMargin m:val=“0”/>
<m:rMargin m:val=“0”/>
<m:defJc m:val=“centerGroup”/>
<m:wrapIndent m:val=“1440”/>
<m:intLim m:val=“subSup”/>
<m:naryLim m:val=“undOvr”/>
</m:mathPr></w:WordDocument>
<![endif]–>
<!–[if gte mso 10]>
/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}<![endif]–>Aspose.Network.Mail.SmtpFailedRecipientsException: At
least one receipents are failed."
The problem is intermittent and there is no pattern. There is no relationship between the message sent and the occurrence of failure.
If we go back to using SmtpClient with the same messages, everything works fine every time.