A EMB145 CREW WAS NOTIFIED AFTER TAKE OFF THAT A VAPOR TRAIL WAS SEEN AS THEY DEPARTED. NO EVIDENCE OF FUEL LEAK WAS SEEN BY THE CREW IN FLIGHT OR AFTER LANDING. A CREW THE NEXT DAY SAID THE AIRCRAFT WAS FERRIED FOR MAINTENANCE.

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THE EVENT OCCURRED WHILE OPERATING FLT. I WAS ACTING AS THE PNF; WHILE CAPT WAS ACTING AS THE PF. PRIOR TO FLT A NORMAL PREFLT WALKAROUND WAS PERFORMED THAT REVEALED NO ABNORMALITIES. THE ACFT WAS FUELED NEAR THE MAX LIMIT OF 11100 LBS. SHORTLY AFTER DEP FROM AN EASTSIDE RWY; DEP CTL NOTIFIED US THAT ZZZ TWR HAD NOTICED A VAPOR TRAIL BEHIND OUR ACFT ON DEP. WE QUERIED ATC REGARDING WHICH SIDE OF THE ACFT IT APPEARED TO HAVE COME FROM. AFTER CONTACTING THE TWR AGAIN; DEP CTL REPLIED THAT THEY BELIEVED IT TO BE THE L WING. THE CAPT AND I EVALED THE SITUATION AND CHKED THE FUEL LOAD; BURN; AND FLOW USING THE EICAS; MFD DISPLAY; AND FMS. FUEL BAL AND BURN WAS NORMAL. WE CONCLUDED THAT DUE TO THE FUEL LOAD BEING NEAR MAX AT TKOF AND THE OUTSIDE AIR TEMP BEING QUITE HIGH; THAT THE TRAIL WAS MOST LIKELY EXCESS FUEL DRAINING FROM THE L FUEL VENT ON THE TKOF ROLL. WE THEN NOTIFIED DEP OF OUR DETERMINATION AND THAT WE WOULD CONTINUE ENRTE TO ZZZ1. THROUGHOUT THE FLT WE CONTINUED TO MONITOR THE SITUATION CLOSELY. THE REMAINDER OF THE FLT WAS NORMAL WITH NO INDICATIONS OF FUEL PROBS. UPON ARR IN ZZZ1 WE ONCE AGAIN COMPARED THE FUEL ON BOARD AND THE FUEL BURN WITH THAT OF THE FLT PLAN; AND DETERMINED THAT THE VALUES WERE NORMAL AND CORRECT. THE FLT ATTENDANT DID NOT RPT SEEING ANY VAPOR TRAIL OR NOTICING ANYTHING ABNORMAL DURING THE FLT. WHILE CONDUCTING THE POSTFLT INSPECTION; THERE WAS NO EVIDENCE OF A SIGNIFICANT FUEL LEAK. THERE WAS A STRONGER THAN NORMAL FUEL ODOR SLICK AREA NEAR THE L UNDER-WING FUEL VENT. THERE WERE NO DRIPS OR LIQUID FUEL PRESENT. WE ONCE AGAIN CONCLUDED THAT THE HIGH FUEL LOAD AND TEMP ON TKOF HAD CAUSED NORMAL VENTING OF FUEL OVERBOARD. WE NOTIFIED THE OUTBOUND CREW OF THE EVENTS AND OF THE FINDINGS OF THE POSTFLT INSPECTION. THE ACFT WAS THEN TURNED OVER TO THE OUTBOUND CREW. INITIALLY DEP'S NOTIFICATION OF A VAPOR TRAIL ALERTED US OF THE EVENT. THE FOLLOWING DAY; WHILE LEAVING FROM THE OVERNIGHT HOTEL; WE ENCOUNTERED THE OUTBOUND CREW FROM THE PREVIOUS DAY; WHO TOLD US THAT CONTRACT MAINT HAD BEEN CONTACTED IN ZZZ1 AND DETERMINED THAT THE ACFT SHOULD BE FERRIED TO ZZZ2 FOR MAINT. APPARENTLY UPON DEP OF THAT FERRY FLT; THE FLT ATTENDANT ON BOARD RPTED A VAPOR TRAIL AND THE CREW RETURNED TO ZZZ1. THIS WAS SECOND HAND INFO TOLD TO US BY THE OUTBOUND CREW. ALL INDICATIONS SHOWED A NORMAL SITUATION AND THE FLT CREW DETERMINED A LOGICAL CAUSE FOR THE EVENT. AT NO TIME WAS EVIDENCE THAT WOULD MERIT THE INTERRUPTION OF THE FLT; SO WE CHOSE TO CONTINUE TO THE DEST.