How to insert line feeds in stringbuilder for SMTP email body
Posted on 2006-06-14
My first post on EE and hopefully one that will help others (once solved) who have stumbled across this issue. I'm new to the point system, so hopefully I have valued this appropriately. If your web app generates email and your email is often misformated with exclamations points, read on.
I have a web application that generates an HTML email back to the user. The email is created dynamically and is different for each user. The body of the email is generated by creating an VB.Net Stringbuilder object (sb) and basically sb.Appending various HTML elements together. My guess is this is a fairly common usage.
For example, if I know the first name of the user, things start out like this:
If firstName.Trim <> "" Then
sb.Append("<p style=""margin-top: 0; margin-bottom: 0""><font face=""Arial"" style=""font-size: 11pt"">Dear " & firstName.Trim & ",</font><br> </p>")
Various paragraphs and info are continuously sb.appended and then the entire SB is converted to a string and passed to an email function. This string can be quite long. 5000 - 10000 characters.
The email function is pretty straightforward. The string is assigned to the email.Body and off it goes (try catch block not shown). The key to this problem is that it goes to an SMTP email server. I've not hit this issue on other email servers.
emailMessage.BodyFormat = Mail.MailFormat.Html
emailMessage.Body = big string assigned here
System.Web.Mail.SmtpMail.SmtpServer = System.Configuration.ConfigurationSettings.AppSettings("MailSvr")
What I noticed immediately is that our host email server seemed to be inserting carriage returns into the body of the message. Most times this just appears as an exclamation point ! and space in the middle of text, but sometimes it really whacks the HTML (especially when it hits in the middle of a tag). After repeated denials from the host that the email server had anything to do with it (wrong!) and lots of searching, I finally discovered that the SMTP server does add carriage returns to email when a line is greater than 990 characters. Apparently the smtp_line_length_limit defaults to 990 and smtp then inserts "<CR><LF><SPACE>" into the long lines.
So that sounded reasonably easy to fix and I happily added "
" throughout my sb.Append lines. Only problem, that doesn't seem to solve the problem. Still got the breaks at 990 characters. I also tried "<LF>" and that seemed to make things better - the exclamation points were gone (the CR part, I think), but still got the spaces every 990 chars.
So the question after all this is, "In VB.net, how do you add a line feed to a stringbuilder object that is recognized by SMTP?" BTW, <br> doesn't seem to count as a line feed and I'm pretty sure vbcrlf is not the answer.
Thanks in advance and for reading this far.