在发送到电子邮件的字符串中使用零对一个换行时，没有换行与双换行

Question

I'm sending a string to an email, and I want one sentence per line like this:

"Loaded LLARY_AR with 0 features
Loaded LLARY_LN with 44 features
Loaded LLARY_PT with 23 features"

But when I add one newline to the string concatenation I get two newlines instead of one, like this:

"Loaded LLARY_AR with 0 features

Loaded LLARY_LN with 44 features

Loaded LLARY_PT with 23 features"

And if I do not include a newline I get this:

"Loaded LLARY_AR with 0 features Loaded LLARY_LN with 44 features Loaded LLARY_PT with 23 features"

Here's the code:

msgemail = ""
for fcl in trnlist:
    try:
        tofc = param["tsde"]+"\\"+param["trema"]+fcl
        fromfc = param["msde"]+"\\"+param["mchema"]+fcl
        arcpy.DeleteFeatures_management(tofc)
        arcpy.Append_management(fromfc, tofc)
        msgemail +="\nLoaded "+fcl+" with "+str(arcpy.GetCount_management(fromfc))+" features"
        del fcl, tofc, fromfc
    except:
        msgemail +="\nUnsuccessful!! "+fcl

emailto = ["email@to","email@to"]
server = smtplib.SMTP('server.here')
header = "Results:\n"
subject = "Data"
mailmessage = header+msgemail+"\n\nCheck log for details"
message = 'Subject: %s\n\n%s' %(subject, mailmessage)
for e in emailto:
    try:
        server.sendmail("email@from",e, message)
    except:
        arcpy.AddMessage(e+" was not sent an email.")
server.quit()

I don't understand why the newline acts in this manner..and a newbie..obviously missing something here.

I found that this works to produce an email that is nicely formated (but does not include the necessary information from the ..GetCount..process):

msgemail +="\nLoaded"+fcl

While these do not result in a nicely formated email:

msgemail +="\nLoaded "+fcl+" with "+str(arcpy.GetCount_management(fromfc))+" features"
msgemail +="\nLoaded "+fromcnt
msgemail +="\nLoaded "+fromcnt+" testing for string at end"

Answer 1

There does not appear to be an issue with the code, there should only be one newline between each of your 'Loaded...' lines.

It is possible that the email client you are using to view the email is interpreting newlines as new paragraphs and inserting that spacing automatically. Try replacing the \\n with <br> and see if that results in the single spacing you expect.

Answer 2

I ran into the same problem using the smtplib by itself. I found that a better way to do it is this:

from email.MIMEBase import MIMEBase
from email.MIMEText import MIMEText
from email.Utils import COMMASPACE, formatdate
from email import Encoders
import os
import smtplib

def send_mail(send_from, send_to, subject, text, files=[], server='mail.server.com'):
    assert type(send_to)==list
    assert type(files)==list
    msg = MIMEMultipart()
    msg['From'] = send_from
    msg['To'] = COMMASPACE.join(send_to)
    msg['Date'] = formatdate(localtime=True)
    msg['Subject'] = subject
    msg.attach( MIMEText(text) )
    for f in files:
        part = MIMEBase('application', "octet-stream")
        part.set_payload( open(f,"rb").read() )
        Encoders.encode_base64(part)
        part.add_header('Content-Disposition', 'attachment; filename="%s"' % os.path.basename(f))
        msg.attach(part)
    smtp = smtplib.SMTP(server)
    mydict = smtp.sendmail(send_from, send_to, msg.as_string())
    smtp.close()
    return mydict

Note the return of the dictionary! The smtp.sendmail will return it with a list of failure tuples if some emails fail to send. If all emails fail to send, an exception is thrown, and if they all succeed, then the dictionary is empty.

You will save yourself grief if you check it.

Answer 3

It may be that the '\\n' should come at the end of a line.

It sounds dumb and may not work, but it might be worth a shot.

msgemail = "\n"
for fcl in trnlist:
    try:
        tofc = param["tsde"]+"\\"+param["trema"]+fcl
        fromfc = param["msde"]+"\\"+param["mchema"]+fcl
        arcpy.DeleteFeatures_management(tofc)
        arcpy.Append_management(fromfc, tofc)
        msgemail +="Loaded "+fcl+" with "+str(arcpy.GetCount_management(fromfc))+" features\n"
        del fcl, tofc, fromfc
    except:
        msgemail +="\nUnsuccessful!! "+fcl

emailto = ["email@to","email@to"]
server = smtplib.SMTP('server.here')
header = "Results:\n"
subject = "Data"
mailmessage = header+msgemail+"\n\nCheck log for details"
message = 'Subject: %s\n\n%s' %(subject, mailmessage)
for e in emailto:
    try:
        server.sendmail("email@from",e, message)
    except:
        arcpy.AddMessage(e+" was not sent an email.")
server.quit()